Golf ball compositions

ABSTRACT

The present invention relates to a golf ball including a core, one or more mantle layers and an outer cover layer, and one or more of the core, one or more mantle layers or outer cover layer includes a partially hydrogenated polybutadiene having a viscosity at 200° C. of less than about 5,000 Pa-sec and a storage modulus (G′) at 1 Hz and 25° C. of greater than about 1×10 7 dyn/cm 2 .

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of U.S. provisional application61/785,657, filed Mar. 14, 2013, which is incorporated herein byreference in its entirety.

The application of synthetic polymer chemistry to the field of sportsequipment has revolutionized the performance of athletes in many sports.One sport in which this is particularly true is golf, especially asrelates to advances in golf ball performance and ease of manufacture.For instance, the earliest golf balls consisted of a leather coverfilled with wet feathers. These “feathery” golf balls were subsequentlyreplaced with a single piece golf ball made from “gutta percha,” anaturally occurring rubber-like material. In the early 1900's, the woundrubber ball was introduced, consisting of a solid rubber core aroundwhich rubber thread was tightly wound with a gutta percha cover.

More modern golf balls can be classified as one-piece, two-piece,three-piece or multi-layered golf balls. One-piece balls are molded froma homogeneous mass of material with a dimple pattern molded thereon.One-piece balls are inexpensive and very durable, but typically do notprovide great distance because of relatively high spin and low velocity.Two-piece balls are made by molding a cover around a solid rubber core.These are the most popular types of balls in use today. In attempts tofurther modify the ball performance, especially in terms of the distancesuch balls travel, and the spin and the feel transmitted to the golferthrough the club on striking the ball, the basic two piece ballconstruction has been further modified by the introduction of additionallayers between the core and outer cover layer. If one additional layeris introduced between the core and outer cover layer a so called“three-piece ball” results, if two additional layers are introducedbetween the core and outer cover layer, a so called “four-piece ball”results, and so on.

Golf ball covers were previously made from balata rubber which wasfavored by some players because the softness of the cover allowed themto achieve spin rates sufficient to allow more precise control of balldirection and distance, particularly on shorter approach shots. Howeverbalata-covered balls, although exhibiting high spin and soft feel, wereoften deficient in terms of the durability of the cover which had apropensity to shear

Accordingly, a variety of golf ball constructions have been developed inan attempt to provide spin rates and a feel approaching those of balatacovered balls, while also providing a golf ball with a higher durabilityand overall distance. This has resulted in the emergence of balls, whichhave a solid rubber core, an outer cover layer, and one or more socalled intermediate layers, as well as the application of new materialsto each of these components.

A material which has been often utilized in more modern golf ballsincludes the various ionomer resins developed in the mid-1960's, by E.I.DuPont de Nemours and Co., and sold under the trademark SURLYN®. Theseionomer resins have, to a large extent, replaced balata as a golf ballcover stock material. More recent developments in the field haveattempted to utilize the various types of ionomers, both singly and inblend compositions to optimize the often conflicting golf ballperformance requirements of high C.O.R. and ball velocity, and coverdurability, with the need for a ball to spin and have a so-called softfeel on shorter iron shots. However, the incorporation of more acid inthe ionomer and/or increasing its degree of neutralization results in amaterial with increased polarity, and hence one which is often lesscompatible with other potential blend materials. Also increasing theacid content of the ionomer while increasing C.O.R. may render the balltoo hard and brittle causing a loss of shot feel, control (i.e., theability to spin the ball) and may render the cover too brittle and proneto premature failure. Finally, the incorporation of more acid in theionomer and/or increasing its degree of neutralization typically resultsin an increase in melt viscosity which in turn greatly decreases theprocessability of these resins. Attempts to mediate these effects byadding softer terpolymeric ionomers to high acid ionomer compositions toadjust the hardness and improve the shot “feel” often result inconcomitant loss of C.O.R. and hence distance.

In an attempt to maintain the spin and feel performance of balata coverswhile improving their durability there has been some use of othersynthetic rubber formulations to prepare golf ball cover and mantlelayers, however to date most synthetic rubber formulations have beenused in golf ball core formulations. Most synthetic rubber formulationsused for the core compositions of modern golf balls are based onpolybutadiene, especially cis-1,4-polybutadiene. In order to tailor theproperties of the core, the polybutadiene is often further formulatedwith crosslinking agents, such as sulfur or peroxides, or byirradiation, as well as co-crosslinking agents such as zinc diacrylate.In addition, the weight and hardness of the core may be further adjustedby the incorporation of various filler materials in the rubberformulation. Thus, there is a great deal of literature concerning suchformulation chemistry and the variation of the rubber composition anddegree of cross linking such that cores may be produced with therequired compression, resilience, hardness and durability.

However, the use of such formulations in other layers of the golf ballis somewhat limited given the manufacturing methods used in theirpreparation. After core formation, any intermediate layers and finallythe golf ball outer cover and are typically formed over the core usingone of three methods: casting, injection molding, or compressionmolding. Injection molding generally involves using a mold having one ormore sets of two hemispherical mold sections that mate to form aspherical cavity during the molding process. The pairs of mold sectionsare configured to define a spherical cavity in their interior whenmated. When used to mold an outer cover layer for a golf ball, the moldsections can be configured so that the inner surfaces that mate to formthe spherical cavity include protrusions configured to form dimples onthe outer surface of the molded cover layer. When used to mold a layeronto an existing structure, such as a ball core, the mold includes anumber of support pins disposed throughout the mold sections. Thesupport pins are configured to be retractable, moving into and out ofthe cavity perpendicular to the spherical cavity surface. The supportpins maintain the position of the core while the molten material flowsthrough the gates into the cavity between the core and the moldsections. The mold itself may be a cold mold or a heated mold.

In contrast, compression molding of a ball cover or intermediate layertypically requires the initial step of making half shells by injectionmolding the layer material into an injection mold. The half shells thenare positioned in a compression mold around a ball core, whereupon heatand pressure are used to mold the half shells into a complete layer overthe core, with or without a chemical reaction such as crosslinking.Compression molding also can be used as a curing step after injectionmolding. In such a process, an outer layer of thermally curable materialis injection molded around a core in a cold mold. After the materialsolidifies, the ball is removed and placed into a mold, in which heatand pressure are applied to the ball to induce curing in the outerlayer.

Of the various cover molding processes, injection molding is mostpreferred, due to the efficiencies gained by its use including a morerapid cycle time, cheaper operating costs and an improved ability toproduce thinner layers around the core and closely control any thicknessvariation. This latter advantage is becoming more important with thedevelopments of multi-layered balls with two or more intermediate layersbetween the core and cover thus requiring thinner layer formation. Suchmultilayered golf balls are often fabricated with chemically distinctlayers to produce various combinations of hardness, modulus and otherproperties in order to tailor the resulting principal performancecategories, including ball velocity, compression, spin and distance.However, in addition to being time consuming and expensive and impartingadditional complexity to golf ball preparation, due to their differingchemical compositions, the individual layers often suffer fromdelamination often manifested as poor shear performance.

There were a number of early attempts to incorporate synthetic cis1,4-polybutadiene rubber, as a layer around a central core or as anouter cover layer. For example, U.S. Pat. No. 3,784,209 exemplifies aball prepared by forming a center of a first cis 1,4-polybutadieneformulation and forming a outer cover layer around it of a second cis1,4-polybutadiene formulation and finally curing the resulting golf ballprecursor in a compression molding step. Also, U.S. Pat. No. 4,625,964exemplifies a golf ball having a central core made from cis1,4-polybutadiene around which was compression molded two half shellspreviously prepared from another cis 1,4-polybutadiene formulation toform a second layer. The ball was completed by injection molding anionomer outer cover layer. U.S. Pat. No. 4,714,253 exemplifies a golfball having a central core formed from a first cis 1,4-polybutadieneformulation followed by forming an second layer from another cis1,4-polybutadiene formulation. Two pre-formed ionomer half shells werethen pressure molded around the two piece solid core to form the finalgolf ball. U.S. Pat. No. 4,848,770 exemplifies a three piece solid golfball having a center produced from a highly filled cis 1,4-polybutadieneformulation and second layer produced from a second unfilled cis1,4-polybutadiene formulation, followed by compression molding twoionomer half shells to form the outer cover layer.

However because of the relatively high viscosity of cis1,4-polybutadiene formulations at normal injection molding temperatures,which becomes even more pronounced if such formulations also includefiller, these formulations are not easily adaptable to traditional thinlayer-forming injection molding techniques. Thus the current evolutionin golf balls technology favors the use of thermoplastic materials suchas ionomers or thermoplastic polyurethane in golf ball covers andintermediate layers, which materials are much more amenable to modernthin layer injection molding techniques.

Thus, it would be highly advantageous to have an injection moldablerubber composition with the soft feel of a rubber such as balata, but ofsufficiently low viscosity to allow the material to be injection molded.It would also be highly advantageous if the properties of such a rubbercomposition could be tailored by similar formulation chemistry to thatwhich has evolved through the use of crosslinked filled polybutadienecompositions used in core construction

The present disclosure provides a golf ball comprising one or morelayers comprising an injection moldable partially hydrogenatedpolybutadiene rubber composition.

The present disclosure also provides processes for preparing a golf ballby injection molding layers of a partially hydrogenated polybutadienerubber compositions with the required curative packages all having asufficiently low viscosity at and below normal peroxide decompositiontemperatures to allow the material to be injection molded to form a golfball followed by compression molding the resulting golf ball or golfball precursor to form a region in the golf ball made from a partiallyhydrogenated polybutadiene rubber.

The present disclosure also provides processes for preparing a golf ballby injection molding half shells of a partially hydrogenatedpolybutadiene rubber compositions having a sufficiently low viscosity atand below normal peroxide decomposition temperatures to allow thematerial to be injection molded to form a half shells, followed bycombining the half shells around a golf ball core or golf ball precursorand compression molding the resulting golf ball or golf ball precursorto form the golf ball or golf ball layer.

SUMMARY

The present invention relates to a golf ball including a core, one ormore mantle layers and an outer cover layer, and one or more of thecore, one or more mantle layers or outer cover layer includes apartially hydrogenated polybutadiene having a viscosity at 200° C. ofless than about 5,000 Pa-sec and a storage modulus (G′) at 1 Hz and 25°C. of greater than about 1×10⁷dyn/cm².

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a three-piece golf ball 1 comprising a solid centeror core 2, a mantle layer 3, and an outer cover layer 4.

FIG. 2 illustrates a four-piece golf ball 1 comprising a core 2, and anouter cover layer 5, an inner mantle layer 3, and an outer mantle layer4.

FIG. 3 illustrates a five-piece golf ball 1 comprising a core 2, and anouter cover layer 5, an inner mantle layer 3, an outer mantle layer 4,and an intermediate mantle layer 6.

DETAILED DESCRIPTION OF INVENTION

Any numerical values recited herein include all values from the lowervalue to the upper value in increments of one unit provided that thereis a separation of at least 2 units between any lower value and anyhigher value. As an example, if it is stated that the amount of acomponent or a value of a process variable is from 1 to 90, preferablyfrom 20 to 80, more preferably from 30 to 70, it is intended that valuessuch as 15 to 85, 22 to 68, 43 to 51, 30 to 32 etc. are expresslyenumerated in this specification. For values, which have less than oneunit difference, one unit is considered to be 0.1, 0.01, 0.001, or0.0001 as appropriate. Thus all possible combinations of numericalvalues between the lowest value and the highest value enumerated hereinare said to be expressly stated in this application.

The term “bimodal polymer” refers to a polymer comprising two mainfractions and more specifically to the form of the polymers molecularweight distribution curve, i.e., the appearance of the graph of thepolymer weight fraction as function of its molecular weight. When themolecular weight distribution curves from these fractions aresuperimposed into the molecular weight distribution curve for the totalresulting polymer product, that curve will show two maxima or at leastbe distinctly broadened in comparison with the curves for the individualfractions. Such a polymer product is called bimodal. It is to be notedhere that also the chemical compositions of the two fractions may bedifferent.

As used herein, the term “block copolymer” is intended to mean a polymercomprising two or more homopolymer subunits linked by covalent bonds.The union of the homopolymer subunits may require an intermediatenon-repeating subunit, known as a junction block. Block copolymers withtwo or three distinct blocks are called diblock copolymers and triblockcopolymers, respectively.

The term “core” is intended to mean the elastic center of a golf ball.The core maybe a unitary core and also be of a so called “dual core”construction. When the term unitary core is used then it is understoodthat any adjacent layers to the core are mantle layers and not corelayers. A dual core is made of up of (i) an interior spherical centercomponent formed from a thermoset material, preferably polybutadiene and(ii) a second region formed around the interior spherical centercomponent, also formed from a thermoset material, and preferablybutadiene. Although the two core regions which constitute the dual coremay both be formed from polybutadiene, each region preferably hasdifferent physical properties such as resilience, hardness or modulusresulting from the use of different crosslinking packages and/orprocessing conditions.

The term “outer cover layer” is intended to mean the outermost layer ofthe golf ball; this is the layer that is directly in contact with paintand/or ink on the surface of the golf ball. If the cover consists of twoor more layers, only the outermost layer is designated the outer coverlayer, and the next layer inward to the direction of the core is knownas the inner cover layer.

The term “fiber” as used herein is a general term for which thedefinition given in Engineered Materials Handbook, Vol. 2, “EngineeringPlastics”, published by A.S.M. International, Metals Park, Ohio, USA, isrelied upon to refer to filamentary materials with a finite length thatis at least 100 times its diameter, which is typically 0.10 to 0.13 mm(0.004 to 0.005 in.). Fibers can be continuous or specific short lengths(discontinuous), normally no less than 3.2 mm (⅛ in.). Although fibersaccording to this definition are preferred, fiber segments, i.e., partsof fibers having lengths less than the aforementioned are alsoconsidered to be encompassed by the invention. Thus, the terms “fibers”and “fiber segments” are used herein. In the claims appearing at the endof this disclosure in particular, the expression “fibers or fibersegments” and “fiber elements” are used to encompass both fibers andfiber segments.

The term “hydrocarbyl” is intended to mean any aliphatic,cycloaliphatic, aromatic, aryl substituted aliphatic, aryl substitutedcycloaliphatic, aliphatic substituted aromatic, or cycloaliphaticsubstituted aromatic groups. The aliphatic or cycloaliphatic groups arepreferably saturated. Likewise, the term “hydrocarbyloxy” means ahydrocarbyl group having an oxygen linkage between it and the carbonatom to which it is attached.

The term “injection moldable” as used herein, and as applied to therubber compositions used as described herein refers to a materialamenable to use in injection molding apparatus designed for use withtypical thermoplastic resins. In one example, the term injectionmoldable composition as applied to the uncrosslinked rubbers used in thepresent disclosure means compositions having a viscosity using a DynamicMechanical Analyzer (DMA) and ASTM D4440 at 200° C. of less than about5,000 Pa-sec, preferably less than about 3,000 Pa-sec, more preferablyless than about 2,000 Pa-sec and even more preferably less than about1,000 Pa-sec. and a storage modulus (G′) at 1 Hz measured using aDynamic Mechanical Analyzer (DMA) and ASTM D4065, and ASTM D4440, at 25°C., and 1 Hz of greater than about 1×10⁷ dyn/cm², preferably greaterthan about 1.5×10⁷ dyn/cm², more preferably greater than about1×10⁸dyn/cm², and most preferably greater than about 2×10⁸ dyn/cm².

The term “mantle layer” is intended to mean any layer(s) in a golf balldisposed between the core (and any core layers) and the innermost coverlayer. Should a ball have three mantle layers, these may bedistinguished as “inner mantle layer” which refers to the mantle layernearest the core and furthest from the outer cover layer, as opposed tothe “outer mantle layer” which refers to the mantle layer furthest fromthe core and closest to the outer cover layer, and as opposed to the“intermediate mantle layer” which refers to the mantle layer between theinner mantle layer and the outer mantle layer. Should a ball have fourmantle layers, these may be distinguished as “inner mantle layer” whichrefers to the mantle layer nearest the core and furthest from the outercover layer, as opposed to the “outer mantle layer” which refers to themantle layer furthest from the core and closest to the outer coverlayer, and as opposed to the “inner intermediate mantle layer” whichrefers to the mantle layer immediately adjacent to and outward of theinner mantle layer and as opposed to the “outer intermediate mantlelayer” which refers to the mantle layer immediately adjacent to andinward of the outer mantle layer and immediately adjacent to and outwardof the inner intermediate mantle layer.

The term “(meth)acrylic acid copolymers” is intended to mean copolymersof methacrylic acid and/or acrylic acid.

The term “(meth)acrylate” is intended to mean an ester of methacrylicacid and/or acrylic acid.

The term “partially neutralized” is intended to mean an ionomer with adegree of neutralization of less than 100 percent. The term “highlyneutralized” is intended to mean an ionomer with a degree ofneutralization of greater than 50 percent. The term “fully neutralized”is intended to mean an ionomer with a degree of neutralization of 100percent.

The term “prepolymer” as used herein is intended to mean any polymericmaterial that can be further processed to form a final polymer materialof a manufactured golf ball, such as, by way of example and notlimitation, a polymerized or partially polymerized material that canundergo additional processing, such as crosslinking.

The term “sports equipment” refers to any item of sports equipment suchas sports clothing, boots, sneakers, clogs, sandals, slip on sandals andshoes, golf shoes, tennis shoes, running shoes, athletic shoes, hikingshoes, skis, ski masks, ski boots, cycling shoes, soccer boots, golfclubs, golf bags, and the like.

The term “thermoplastic” as used herein is intended to mean a materialthat is capable of softening or melting when heated and of hardeningagain when cooled. Thermoplastic polymer chains often are notcross-linked or are lightly crosslinked using a chain extender, but theterm “thermoplastic” as used herein may refer to materials thatinitially act as thermoplastics, such as during an initial extrusionprocess or injection molding process, but which also may be crosslinked,such as during a compression molding step to form a final structure.

The term “thermoset” as used herein is intended to mean a material thatcrosslinks or cures via interaction with as crosslinking or curingagent. Crosslinking may be induced by energy, such as heat (generallyabove 200° C.), through a chemical reaction (by reaction with a curingagent), or by irradiation. The resulting composition remains rigid whenset, and does not soften with heating. Thermosets have this propertybecause the long-chain polymer molecules cross-link with each other togive a rigid structure. A thermoset material cannot be melted andre-molded after it is cured. Thus thermosets do not lend themselves torecycling unlike thermoplastics, which can be melted and re-molded.

The term “thermoplastic polyurethane” as used herein is intended to meana material prepared by reaction of a prepared by reaction of adiisocyanate with a polyol, and optionally addition of a chain extender.

The term “thermoplastic polyurea” as used herein is intended to mean amaterial prepared by reaction of a prepared by reaction of adiisocyanate with a polyamine, with optionally addition of a chainextender.

The term “thermoset polyurethane” as used herein is intended to mean amaterial prepared by reaction of a diisocyanate with a polyol (or aprepolymer of the two), and a curing agent.

The term “thermoset polyurea” as used herein is intended to mean amaterial prepared by reaction of a diisocyanate with a polyamine (or aprepolymer of the two) and a curing agent.

The term “unimodal polymer” refers to a polymer comprising one mainfraction and more specifically to the form of the polymers molecularweight distribution curve, i.e., the molecular weight distribution curvefor the total polymer product shows only a single maximum.

The term “urethane prepolymer” as used herein is intended to mean thereaction product of diisocyanate and a polyol.

The term “urea prepolymer” as used herein is intended to mean thereaction product of a diisocyanate and a polyamine.

The term “zwitterion” as used herein is intended to mean a form of thecompound having both an amine group and carboxylic acid group, whereboth are charged and where the net charge on the compound is neutral.

The present invention can be used in forming golf balls of any desiredsize. “The Rules of Golf” by the USGA dictate that the size of acompetition golf ball must be at least 1.680 inches in diameter;however, golf balls of any size can be used for leisure golf play. Thepreferred diameter of the golf balls is from about 1.680 inches to about1.800 inches. The more preferred diameter is from about 1.680 inches toabout 1.760 inches. A diameter of from about 1.680 inches to about 1.740inches is most preferred; however diameters anywhere in the range offrom 1.70 to about 2.0 inches can be used. Oversize golf balls withdiameters above about 1.760 inches to as big as 2.75 inches are alsowithin the scope of the invention.

The golf balls of the present invention comprise an injection moldablepartially hydrogenated polybutadiene (“PHPB”) in one or more of theircore, mantle and outer cover layers.

Partially Hydrogenated Polybutadiene (“PHPB”).

In general, 1,3-butadiene can be polymerized to yield cis, trans andvinyl polymers as shown in the composite of each depicted in FIG. 1.

The properties of the resulting isomeric forms of polybutadiene differas they can result from cis and trans linkages (both resulting from1,4-addition) as well as linkages resulting from 1,2-addition whichresults in vinyl group side chains in the polymer. For example, “highcis” polybutadiene is characterized by a high proportion of cis linkages(typically over 92%) and a small proportion of vinyl groups (less than4%). It typically has high elasticity and thus is often used in typicalgolf ball core formulations. So-called “low cis” polybutadiene typicallycontains about 35% cis, 55% trans and 10% vinyl and has a highliquid-glass transition, and can be advantageously used as an additivein plastics due to its low contents of gels. So-called “high trans”polybutadiene is a crystalline polymer (i.e. not an elastomer) whichmelts at about 80° C. and has been used for golf ball cover layers, dueto its similarity in structure to polyisoprene balata rubber.“High-vinyl” polybutadiene typically has over 70% vinyl contentresulting from a 1,2-addition mechanism. In addition to these kinds ofconnectivity, polybutadienes can also differ in terms of their branchingtheir molecular weights and molecular weight distributions.

The polybutadiene to be hydrogenated to form the PHPB for use in thegolf ball of the present invention may contain of from about 20 to about80 preferably of from about 30 to about 70, and more preferably of fromabout 45 to about 65 mol percent trans 1,4-addition. The polybutadieneto be hydrogenated to form the PHPB for use in the golf ball of thepresent invention may contain of from about 10 to about 70, preferablyof from about 20 to about 60, and more preferably of from about andabout 25 to about 45 mole percent cis 1,4-addition. The remainder of thepolymer is formed by 1,2-addition of the 1,3-butadiene to give the 1,2vinyl content. These polymers are prepared by polymerizing butadiene ina suitable solvent (which does not adversely affect the polymerization,for example, a hydrocarbon solvent), in the presence of a suitableorgano-metallic catalyst, for example, a hydrocarbyllithium catalyst andpreferably in the presence of a Lewis base.

The weight average molecular weight of the polybutadiene to behydrogenated to form the PHPB product is in the range of from about50,000 to about 300,000, preferably of from about 75,000 to about250,000, even more preferably of from about 90,000 to about 200,000.

The lithium-based catalysts employed for the polymerization of1,3-butadiene may comprise metallic lithium, organolithium compounds, orother compounds of lithium in which lithium can displace hydrogen fromwater. Organolithium compounds, as used herein, include the varioushydrocarbyllithiums, i.e., hydrocarbons in which one or more hydrogenatoms have been replaced by lithium, and adducts of lithium withpolycyclic aromatic compounds. Suitable hydrocarbyllithiums include, forinstance, alkyllithium compounds, such as methyllithium, ethyllithium,butyllithium, amyllithium, hexyllithium, 2-ethylhexyllithium andn-hexyldecyllithium.

The concentration of the lithium catalyst employed can vary widelydepending on the particular catalyst employed, reaction conditions, theproduct desired, etc. For example, concentrations of catalyst, based onsolvent and actual weight of lithium in the catalyst, can vary fromabout 0.001 to about 10 percent or greater.

Lewis bases which can be employed include ethers, thioethers, tertiaryamines and the like, in concentrations of about 0.5 to about 20 percent,based on solvent. The actual concentration of the Lewis base will dependupon the particular Lewis base used and the polymer desired.

The organic ethers that are employed include alkyl, aryl, aralkyl,alkaryl and cyclic ethers such as dioxane and tetrahydrofuran. Ethers ofglycols may also be employed, for example, the dimethyl ether ofdiethylene glycol. The corresponding thioethers and tertiary amines canalso be employed.

Aromatic, aliphatic and alicyclic hydrocarbon solvents can be employed.Alicyclic solvents include cyclohexane. Aliphatic solvents includeheptane, pentane, butane, hexane and the like. Aromatic solvents includebenzene, toluene and xylenes.

Polymerization temperatures in the range of 10°-100° C. can be used.Pressures of atmospheric to ten or twenty atmospheres are employed so asto maintain a high concentration of the reactant in the liquid phase.The concentration of the butadiene in the solvent can vary widely suchas from 5 to 75 percent.

The polymerization is carried out in an inert atmosphere, in the absenceof air, carbon dioxide, oxygen and the like. It can be carried out underan atmosphere of an inert gas such as pure nitrogen, helium, argon,etc., in vacuum, or under a pressure of inert organic materials.

Hydrogenation to form the PHPB used in the golf balls of the presentinvention may be accomplished by any of a number of hydrogenationtechniques well known in the art. U.S. Pat. No. 4,187,360, the entirecontents of which are incorporated by reference herein, discloses ahydrogenated polybutadiene prepared from a polybutadiene prepared usingan organolithium-based catalyst system. The patent also discloses thatthe resulting polybutadiene can be subsequently hydrogenated using anumber of hydrogenation catalysts, such as nickel-kieselguhr, Raneynickel, copper chromite, molybdenum sulfide, finely divided platinum,finely divided palladium, platinum oxide, copper chromium oxide, and thelike.

In addition, U.S. Pat. No. 3,663,635, DE 3401983, U.S. Pat. No.5,039,755, U.S. Pat. No. 5,132,372, EP 339986, EP 434469, EP 544304, EP795564, EP 810231, and WO 9525130 describe catalyst systems for thehydrogenation of olefinically unsaturated compounds, and in particularfor the hydrogenation of conjugated diene (co)polymers.

More particularly, U.S. Pat. No. 3,663,635, the entire contents of whichare incorporated by reference herein, for instance, describes catalystsystems for the hydrogenation of unsaturated compounds such as olefinsbased on titanocenes of the formula TiX₂Y₂ in which X represents halide,amino, hydrocarbylamino, thio, carboxylate, alkoxide or a hydrogen atom,and Y is cyclopentadienyl, indenyl, fluorenyl or allyl substituted ornot, which are reacted with an aluminium hydride.

U.S. Pat. No. 5,039,755, the entire contents of which are incorporatedby reference herein describes the hydrogenation of a conjugated diene(co)polymer that is terminated with hydrogen in the presence of atitanocene to which sec-butyllithium is added.

U.S. Pat. No. 5,132,372 concerns the use of methyl benzoate as promotingagent in titanocene-based hydrogenation reactions. Further promoters aredisclosed in U.S. Pat. No. 5,173,537 which describes the deactivation oflithium hydride by addition of various reagents prior to hydrogenationand titanium catalyst addition.

In addition, U.S. Pat. No. 6,313,230 and U.S. Pat. No. 6,465,609, theentire contents of each of which are incorporated by reference herein,which disclose the use of a hydrogenation catalyst compositioncomprising an organotitanium compound.

The polybutadiene prepared above may be directly hydrogenated withoutseparating the polybutadiene from solution or isolated and dissolvedprior to hydrogenation. Thereupon the hydrogenated polymer can beseparated from solution by standard procedures.

Typically the polybutadiene is diluted with an inert solvent, such asthose previously mentioned, or in the original polymerization medium andthe polymer solution and hydrogenation catalyst are added to a highpressure autoclave. The autoclave is pressured with hydrogen and thenheated, while mixing. The reactor is then depressurized, the catalystremoved by filtering, and the hydrogenated polymer recovered from thesolvent by conventional stripping procedures.

The hydrogenation catalyst will generally be used in an amount of 0.1 to20 weight percent based upon the weight of the polymer to behydrogenated. The specific amount of catalyst employed depends somewhatupon the specific catalyst used.

The polymers can be recovered by procedures well known in the art. Forexample, polar materials, such as water or C₁ to C₅ alkanols can beadded to inactivate the catalyst After termination of the reaction, thehydrocarbon solution is washed with water or dilute mineral acid.Alternatively, the active polymer solution can be treated with hydratedclays, such as natural Attapulgus clay, which functions to bothinactivate the catalyst and to chemically absorb the lithium component.The polymer may then be recovered by filtering the resultant polymersolution, drying if necessary, and stripping of remaining inert diluentat elevated temperatures. For the isolation of higher molecular weightpolymers steam stripping or precipitation with anti-solvents ispreferred.

The polymers can be hydrogenated according to the following ranges ofreaction conditions. Reaction pressures are preferably in the range ofatmospheric to 3,000 psig. The temperature can range from about 25° C.up to the degradation temperature of the polymer. The reaction times canbe in the range of 1 to 24 hours. The amount of catalyst required is afunction of the temperature of hydrogenation.

The hydrogenation is carried out to such a degree that of from about 25to about 75, preferably of from about 30 to about 70, more preferably offrom about 35 to about 65 and even more preferably of from about 40 toabout 60% of double bonds in the original polybutadiene have beenhydrogenated and are thus saturated.

Given the unsaturation present in the elastomer backbone the PHPBcompositions are also amenable to the various methods used to crosslinkelastomeric rubber compositions including vulcanization, and radiationcrosslinking. Radiation can be applied to the unsaturated polymermixture by any known method, including using microwave or gammaradiation, or an electron beam device. Additives may also be used toimprove radiation curing of the diene polymer.

Preferably the PHPB composition is crosslinked using the typicalperoxide-based crosslinking systems typically used in golf ball corepreparation. Suitable cross-linking agents include peroxides, sulfurcompounds, or other known chemical cross-linking agents, as well asmixtures of these. Non-limiting examples of suitable cross-linkingagents include primary, secondary, or tertiary aliphatic or aromaticorganic peroxides. Peroxides containing more than one peroxy group canbe used, such as 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and1,4-di-(2-tert-butyl peroxyisopropyl)benzene. Both symmetrical andasymmetrical peroxides can be used, for example, tert-butyl perbenzoateand tert-butyl cumyl peroxide. Peroxides incorporating carboxyl groupsalso are suitable. The decomposition of peroxides used as cross-linkingagents in the present invention can be brought about by applying thermalenergy, shear, irradiation, reaction with other chemicals, or anycombination of these. Both homolytically and heterolytically decomposedperoxide can be used in the present invention. Non-limiting examples ofsuitable peroxides include: diaacetyl peroxide; di-tert-butyl peroxide;dibenzoyl peroxide; dicumyl peroxide;2,5-dimethyl-2,5-di(benzoylperoxy)hexane;1,4-bis-(t-butylperoxyisopropyl)benzene; t-butylperoxybenzoate;2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3, such as Trigonox 145-45B,marketed by Akrochem Corp. of Akron, Ohio; 1,1-bis(t-butylperoxy)-3,3,5tri-methylcyclohexane, such as Varox 231-XL, marketed by R.T. VanderbiltCo., Inc. of Norwalk, Conn.; and di-(2,4-dichlorobenzoyl)peroxide. Thecross-linking agents can be blended in total amounts of about 0.05 partto about 5 parts, more preferably about 0.2 part to about 3 parts, andmost preferably about 0.2 part to about 2 parts, by weight of thecross-linking agents per 100 parts by weight of the unsaturated polymer.

Each cross-linking agent has a characteristic decomposition temperatureat which 50% of the cross-linking agent has decomposed when subjected tothat temperature for a specified time period (t_(1/2)). For example,1,1-bis-(t-butylperoxy)-3,3,5-tri-methylcyclohexane at t_(1/2)=0.1 hrhas a decomposition temperature of 138° C. and2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3 at t_(1/2)=0.1 hr has adecomposition temperature of 182° C. Two or more cross-linking agentshaving different characteristic decomposition temperatures at the samet_(1/2) may be blended in the composition. For example, where at leastone cross-linking agent has a first characteristic decompositiontemperature less than 150° C., and at least one cross-linking agent hasa second characteristic decomposition temperature greater than 150° C.,the composition weight ratio of the at least one cross-linking agenthaving the first characteristic decomposition temperature to the atleast one cross-linking agent having the second characteristicdecomposition temperature can range from 5:95 to 95:5, or morepreferably from 10:90 to 50:50.

Suitable co-cross-linking agents, may be a metal salt of an unsaturatedcarboxylic acid. Examples of these include zinc and magnesium salts ofunsaturated fatty acids having 3 to 8 carbon atoms, such as acrylicacid, methacrylic acid, maleic acid, and fumaric acid, palmitic acidwith the zinc salts of acrylic and methacrylic acid being mostpreferred. The unsaturated carboxylic acid metal salt can be blended ina rubber either as a preformed metal salt, or by introducing anα,β-unsaturated carboxylic acid and a metal oxide or hydroxide into therubber composition, and allowing them to react in the rubber compositionto form a metal salt. The unsaturated carboxylic acid metal salt can beblended in any desired amount, but preferably in amounts of about 10parts to about 60 parts by weight of the unsaturated carboxylic acid per100 parts by weight of the synthetic rubber.

The crosslinking package for the PHPB compositions may also incorporateone or more of the so-called “peptizers”. The peptizer preferablycomprises an organic sulfur compound and/or its metal or non-metal salt.Examples of such organic sulfur compounds include thiophenols, such aspentachlorothiophenol, 4-butyl-o-thiocresol, 4 t-butyl-p-thiocresol, and2-benzamidothiophenol; thiocarboxylic acids, such as thiobenzoic acid;4,4′ dithio dimorpholine; and, sulfides, such as dixylyl disulfide,dibenzoyl disulfide; dibenzothiazyl disulfide;di(pentachlorophenyl)disulfide; dibenzamido diphenyldisulfide (DBDD),and alkylated phenol sulfides, such as VULTAC marketed by AtofinaChemicals, Inc. of Philadelphia, Pa. Preferred organic sulfur compoundsinclude pentachlorothiophenol, and dibenzamido diphenyldisulfide.

Examples of the metal salt of an organic sulfur compound include sodium,potassium, lithium, magnesium calcium, barium, and cesium and zinc saltsof the above-mentioned thiophenols and thiocarboxylic acids, with thezinc salt of pentachlorothiophenol being most preferred.

Examples of the non-metal salt of an organic sulfur compound includeammonium salts of the above-mentioned thiophenols and thiocarboxylicacids wherein the ammonium cation has the general formula [NR¹R²R³R⁴]⁺where R¹, R², R³ and R⁴ are selected from the group consisting ofhydrogen, a C₁-C₂₀ aliphatic, cycloaliphatic or aromatic moiety, and anyand all combinations thereof, with the most preferred being the NH₄⁺-salt of pentachlorothiophenol.

Additional peptizers include aromatic or conjugated peptizers comprisingone or more heteroatoms, such as nitrogen, oxygen and/or sulfur. Moretypically, such peptizers are heteroaryl or heterocyclic compoundshaving at least one heteroatom, and potentially plural heteroatoms,where the plural heteroatoms may be the same or different. Suchpeptizers include peptizers such as an indole peptizer, a quinolinepeptizer, an isoquinoline peptizer, a pyridine peptizer, purinepeptizer, a pyrimidine peptizer, a diazine peptizer, a pyrazinepeptizer, a triazine peptizer, a carbazole peptizer, or combinations ofsuch peptizers.

Suitable peptizers also may include one or more additional functionalgroups, such as halogens, particularly chlorine; a sulfur-containingmoiety exemplified by thiols, where the functional group is sulfhydryl(—SH), thioethers, where the functional group is —SR, disulfides,(R₁S—SR₂), etc.; and combinations of functional groups. Such peptizersare more fully disclosed in U.S. Pat. No. 8,030,411 in the name of HyunKim et al, the entire contents of which are herein incorporated byreference. A most preferred example is 2, 3, 5,6-tetrachloro-4-pyridinethiol (TCPT).

The peptizer, if employed is present in an amount up to about 10, fromabout 0.01 to about 10, preferably of from about 0.10 to about 7, morepreferably of from about 0.15 to about 5 parts by weight per 100 partsby weight of the synthetic rubber component.

The PHPB crosslinking compositions can also comprise one or moreaccelerators of one or more classes. Accelerators are added to anunsaturated polymer to increase the vulcanization rate and/or decreasethe vulcanization temperature. Accelerators can be of any class knownfor rubber processing including mercapto-, sulfenamide-, thiuram,dithiocarbamate, dithiocarbamyl-sulfenamide, xanthate, guanidine, amine,thiourea, and dithiophosphate accelerators. Specific commercialaccelerators include 2-mercaptobenzothiazole and its metal or non-metalsalts, such as Vulkacit Mercapto C, Mercapto MGC, Mercapto ZM-5, and ZMmarketed by Bayer AG of Leverkusen, Germany, Nocceler M, Nocceler MZ,and Nocceler M-60 marketed by Ouchisinko Chemical Industrial Company,Ltd. of Tokyo, Japan, and MBT and ZMBT marketed by Akrochem Corporationof Akron, Ohio. A more complete list of commercially availableaccelerators is given in The Vanderbilt Rubber Handbook: 13^(th) Edition(1990, R.T. Vanderbilt Co.), pp. 296-330, in Encyclopedia of PolymerScience and Technology, Vol. 12 (1970, John Wiley & Sons), pp. 258-259,and in Rubber Technology Handbook (1980, Hanser/Gardner Publications),pp. 234-236. Preferred accelerators include 2-mercaptobenzothiazole(MBT) and its salts. The PHPB composition can further incorporate fromabout 0.1 part to about 10 parts by weight of the accelerator per 100parts by weight of the rubber. More preferably, the ball composition canfurther incorporate from about 0.2 part to about 5 parts, and mostpreferably from about 0.5 part to about 1.5 parts, by weight of theaccelerator per 100 parts by weight of the rubber.

F. Polymer Components

The PHPB compositions may be used directly to prepare the core, outercover layer and/or one or more intermediate layers of the golf balls ofthe present invention or they may be further blended with additionalpolymers prior to or after crosslinking and which additional polymersmay also be used as a separate component of the core, cover layer orintermediate layer of the golf balls of the present invention. Theseadditional polymers may include, without limitation, other synthetic andnatural rubbers, including the polyalkenamers, cis-1,4-polybutadiene,trans-1,4-polybutadiene, 1,2-polybutadiene, cis-polyisoprene,trans-polyisoprene, polychloroprene, polybutylene, styrene-butadienerubber, styrene-butadiene-styrene block copolymer and partially andfully hydrogenated equivalents, styrene-isoprene-styrene block copolymerand partially and fully hydrogenated equivalents, nitrile rubber,silicone rubber, and polyurethane, as well as mixtures of these,carboxyl-terminated butadiene (CTBN) and butadiene grafted with maleicanhydride (BMA), thermoset polymers such as thermoset polyurethanes andthermoset polyureas, as well as thermoplastic polymers includingthermoplastic elastomers such as unimodal ethylene/carboxylic acidcopolymers, unimodal ethylene/carboxylic acid/carboxylate terpolymers,bimodal ethylene/carboxylic acid copolymers, bimodal ethylene/carboxylicacid/carboxylate terpolymers, unimodal ionomers, bimodal ionomers,modified unimodal ionomers, modified bimodal ionomers, thermoplasticpolyurethanes, thermoplastic polyureas, polyesters, copolyesters,polyamides, copolyamides, polycarbonates, polyolefins, polyphenyleneoxide, polyphenylene sulfide, diallyl phthalate polymer, polyimides,polyvinyl chloride, polyamide-ionomer, polyurethane-ionomer, polyvinylalcohol, polyarylate, polyacrylate, polyphenylene ether, impact-modifiedpolyphenylene ether, polystyrene, high impact polystyrene,acrylonitrile-butadiene-styrene copolymer styrene-acrylonitrile (SAN),acrylonitrile-styrene-acrylonitrile, styrene-maleic anhydride (S/MA)polymer, styrenic copolymer, functionalized styrenic copolymer,functionalized styrenic terpolymer, styrenic terpolymer, cellulosepolymer, liquid crystal polymer (LCP), ethylene-propylene-dieneterpolymer (EPDM), ethylene-vinyl acetate copolymers (EVA),ethylene-propylene copolymer, ethylene vinyl acetate, polyurea, andpolysiloxane and any and all combinations thereof.

The olefinic thermoplastic elastomers include metallocene-catalyzedpolyolefins, ethylene-octene copolymer, ethylene-butene copolymer, andethylene-propylene copolymers all with or without controlled tacticityas well as blends of polyolefins having ethyl-propylene-non-conjugateddiene terpolymer, rubber-based copolymer, and dynamically vulcanizedrubber-based copolymer. Examples of these include products sold underthe trade names SANTOPRENE, DYTRON, VISAFLEX, and VYRAM by AdvancedElastomeric Systems of Houston, Tex., and SARLINK by DSM of Haarlen, theNetherlands.

Examples of rubber-based thermoplastic elastomers include multiblockrubber-based copolymers, particularly those in which the rubber blockcomponent is based on butadiene, isoprene, or ethylene/butylene. Thenon-rubber repeating units of the copolymer may be derived from anysuitable monomers, including meth(acrylate) esters, such as methylmethacrylate and cyclohexylmethacrylate, and vinyl arylenes, such asstyrene. Examples of styrenic copolymers are resins manufactured byKraton Polymers (formerly of Shell Chemicals) under the trade namesKRATON D (for styrene-butadiene-styrene and styrene-isoprene-styrenetypes) and KRATON G (for styrene-ethylene-butylene-styrene andstyrene-ethylene-propylene-styrene types) and Kuraray under the tradename SEPTON. Examples of randomly distributed styrenic polymers includeparamethylstyrene-isobutylene (isobutene) copolymers developed byExxonMobil Chemical Corporation and styrene-butadiene random copolymersdeveloped by Chevron Phillips Chemical Corp.

The PHPB compositions may also be used in blends with copolyesterthermoplastic elastomers which include polyether ester block copolymers,polylactone ester block copolymers, and aliphatic and aromaticdicarboxylic acid copolymerized polyesters. Polyether ester blockcopolymers are copolymers comprising polyester hard segments polymerizedfrom a dicarboxylic acid and a low molecular weight diol, and polyethersoft segments polymerized from an alkylene glycol having 2 to 10 atoms.Polylactone ester block copolymers are copolymers having polylactonechains instead of polyether as the soft segments discussed above forpolyether ester block copolymers. Aliphatic and aromatic dicarboxyliccopolymerized polyesters are copolymers of an acid component selectedfrom aromatic dicarboxylic acids, such as terephthalic acid andisophthalic acid, and aliphatic acids having 2 to 10 carbon atoms withat least one diol component, selected from aliphatic and alicyclic diolshaving 2 to 10 carbon atoms. Blends of aromatic polyester and aliphaticpolyester also may be used for these. Examples of these include productsmarketed under the trade names HYTREL by E.I. DuPont de Nemours &Company, and SKYPEL by S.K. Chemicals of Seoul, South Korea.

Examples of other thermoplastic elastomers suitable as additionalpolymer components include those having functional groups, such ascarboxylic acid, maleic anhydride, glycidyl, norbonene, and hydroxylfunctionalities. An example of these includes a block polymer having atleast one polymer block A comprising an aromatic vinyl compound and atleast one polymer block B comprising a conjugated diene compound, andhaving a hydroxyl group at the terminal block copolymer, or itshydrogenated product. An example of this polymer is sold under the tradename SEPTON HG-252 by Kuraray Company of Kurashiki, Japan. Otherexamples of these include: maleic anhydride functionalized triblockcopolymer consisting of polystyrene end blocks andpoly(ethylene/butylene), sold under the trade name KRATON FG 1901X byShell Chemical Company; maleic anhydride modified ethylene-vinyl acetatecopolymer, sold under the trade name FUSABOND by E.I. DuPont de Nemours& Company; ethylene-isobutyl acrylate-methacrylic acid terpolymer, soldunder the trade name NUCREL by E.I. DuPont de Nemours & Company;ethylene-ethyl acrylate-methacrylic anhydride terpolymer, sold under thetrade name BONDINE AX 8390 and 8060 by Sumitomo Chemical Industries;brominated styrene-isobutylene copolymers sold under the trade nameBROMO XP-50 by Exxon Mobil Corporation; and resins having glycidyl ormaleic anhydride functional groups sold under the trade name LOTADER byElf Atochem of Puteaux, France.

The other polymer materials may also include the polyamides. The term“polyamide” as used herein includes both homopolyamides andcopolyamides. Illustrative polyamides for use in thepolyalkenamer/polyamide compositions include those obtained by: (1)polycondensation of (a) a dicarboxylic acid, such as oxalic acid, adipicacid, sebacic acid, terephthalic acid, isophthalic acid, or1,4-cyclohexanedicarboxylic acid, with (b) a diamine, such asethylenediamine, tetramethylenediamine, pentamethylenediamine,hexamethylenediamine, decamethylenediamine, 1,4-cyclohexyldiamine orm-xylylenediamine; (2) a ring-opening polymerization of cyclic lactam,such as ε-caprolactam or ω-laurolactam; (3) polycondensation of anaminocarboxylic acid, such as 6-aminocaproic acid, 9-aminononanoic acid,11-aminoundecanoic acid or 12-aminododecanoic acid; (4) copolymerizationof a cyclic lactam with a dicarboxylic acid and a diamine; or anycombination of (1)-(4). In certain examples, the dicarboxylic acid maybe an aromatic dicarboxylic acid or a cycloaliphatic dicarboxylic acid.In certain examples, the diamine may be an aromatic diamine or acycloaliphatic diamine. Specific examples of suitable polyamides includepolyamide 6; polyamide 11; polyamide 12; polyamide 4,6; polyamide 6,6;polyamide 6,9; polyamide 6,10; polyamide 6,12; polyamide MXD6; PA12, CX;PA12, IT; PPA; PA6, IT; and PA6/PPE. Also included are the crosslinkedpolyamide compositions descried in copending application 61/746,540filed on the 27^(th) of December 2012 in the name of the Taylor MadeColf Co. Inc and incorporated herein by reference in its entirety.

The polyamide (which may a polyamide as described above) may also beblended with a functional polymer modifier of. The functional polymermodifier of the polyamide can include copolymers or terpolymers having aglycidyl group, hydroxyl group, maleic anhydride group or carboxylicgroup, collectively referred to as functionalized polymers. Thesecopolymers and terpolymers may comprise an α-olefin. Examples ofsuitable α-olefins include ethylene, propylene, 1-butene, 1-pentene,3-methyl-1-butene, 1-hexene, 4-methyl-1-petene, 3-methyl-1-pentene,1-octene, 1-decene-, 1-dodecene, 1-tetradecene, 1-hexadecene,1-octadecene, 1-eicocene, 1-dococene, 1-tetracocene, 1-hexacocene,1-octacocene, and 1-triacontene. One or more of these α-olefins may beused.

Examples of suitable glycidyl groups in copolymers or terpolymers in thepolymeric modifier include esters and ethers of aliphatic glycidyl, suchas allylglycidylether, vinylglycidylether, glycidyl maleate anditaconatem glycidyl acrylate and methacrylate, and also alicyclicglycidyl esters and ethers, such as 2-cyclohexene-1-glycidylether,cyclohexene-4,5 diglyxidylcarboxylate, cyclohexene-4-glycidylcarboxylate, 5-norboenene-2-methyl-2-glycidyl carboxylate, andendocis-bicyclo(2,2,1)-5-heptene-2,3-diglycidyl dicarboxylate. Thesepolymers having a glycidyl group may comprise other monomers, such asesters of unsaturated carboxylic acid, for example, alkyl(meth)acrylatesor vinyl esters of unsaturated carboxylic acids. Polymers having aglycidyl group can be obtained by copolymerization or graftpolymerization with homopolymers or copolymers.

Examples of suitable terpolymers having a glycidyl group include LOTADERAX8900 and AX8920, marketed by Atofina Chemicals, ELVALOY marketed byE.I. Du Pont de Nemours & Co., and REXPEARL marketed by NipponPetrochemicals Co., Ltd. Additional examples of copolymers comprisingepoxy monomers and which are suitable for use within the scope of thepresent invention include styrene-butadiene-styrene block copolymers inwhich the polybutadiene block contains epoxy group, andstyrene-isoprene-styrene block copolymers in which the polyisopreneblock contains epoxy. Commercially available examples of these epoxyfunctional copolymers include ESBS A1005, ESBS A1010, ESBS A1020, ESBSAT018, and ESBS AT019, marketed by Daicel Chemical Industries, Ltd.

Examples of polymers or terpolymers incorporating a maleic anhydridegroup suitable for use within the scope of the present invention includemaleic anhydride-modified ethylene-propylene copolymers, maleicanhydride-modified ethylene-propylene-diene terpolymers, maleicanhydride-modified polyethylenes, maleic anhydride-modifiedpolypropylenes, ethylene-ethylacrylate-maleic anhydride terpolymers, andmaleic anhydride-indene-styrene-cumarone polymers. Examples ofcommercially available copolymers incorporating maleic anhydrideinclude: BONDINE, marketed by Sumitomo Chemical Co., such as BONDINEAX8390, an ethylene-ethyl acrylate-maleic anhydride terpolymer having acombined ethylene acrylate and maleic anhydride content of 32% byweight, and BONDINE TX TX8030, an ethylene-ethyl acrylate-maleicanhydride terpolymer having a combined ethylene acrylate and maleicanhydride content of 15% by weight and a maleic anhydride content of 1%to 4% by weight; maleic anhydride-containing LOTADER 3200, 3210, 6200,8200, 3300, 3400, 3410, 7500, 5500, 4720, and 4700, marketed by AtofinaChemicals; EXXELOR VA1803, a maleic anyhydride-modifiedethylene-propylene copolymer having a maleic anyhydride content of 0.7%by weight, marketed by Exxon Chemical Co.; and KRATON FG 1901×, a maleicanhydride functionalized triblock copolymer having polystyrene endblocksand poly(ethylene/butylene) midblocks, marketed by Shell Chemical.

Preferably the functional polymer component is a maleic anhydridegrafted polymers preferably maleic anhydride grafted polyolefins (forexample, Exxellor VA1803). Styrenic block copolymers are copolymers ofstyrene with butadiene, isoprene, or a mixture of the two. Additionalunsaturated monomers may be added to the structure of the styrenic blockcopolymer as needed for property modification of the resultingSBC/urethane copolymer. The styrenic block copolymer can be a diblock ora triblock styrenic polymer. Examples of such styrenic block copolymersare described in, for example, U.S. Pat. No. 5,436,295 to Nishikawa etal. The styrenic block copolymer can have any known molecular weight forsuch polymers, and it can possess a linear, branched, star, dendrimericor combination molecular structure. The styrenic block copolymer can beunmodified by functional groups, or it can be modified by hydroxylgroup, carboxyl group, or other functional groups, either in its chainstructure or at one or more terminus. The styrenic block copolymer canbe obtained using any common process for manufacture of such polymers.The styrenic block copolymers also may be hydrogenated using well-knownmethods to obtain a partially or fully saturated diene monomer block.

Other preferred materials suitable for use as additional polymers in thepresently disclosed compositions include polyester thermoplasticelastomers marketed under the tradename SKYPEL™ by SK Chemicals of SouthKorea, or diblock or triblock copolymers marketed under the tradenameSEPTON™ by Kuraray Corporation of Kurashiki, Japan, and KRATON™ byKraton Polymers Group of Companies of Chester, United Kingdom. Forexample, SEPTON HG 252 is a triblock copolymer, which has polystyreneend blocks and a hydrogenated polyisoprene midblock and has hydroxylgroups at the end of the polystyrene blocks. HG-252 is commerciallyavailable from Kuraray America Inc. (Houston, Tex.).

A further example of a preferred materials suitable for use asadditional polymers in the presently disclosed compositions is aspecialty propylene elastomer as described, for example, in US2007/0238552 A1, and incorporated herein by reference in its entirety. Aspecialty propylene elastomer includes a thermoplasticpropylene-ethylene copolymer composed of a majority amount of propyleneand a minority amount of ethylene. These copolymers have at leastpartial crystallinity due to adjacent isotactic propylene units.Although not bound by any theory, it is believed that the crystallinesegments are physical crosslinking sites at room temperature, and athigh temperature (i.e., about the melting point), the physicalcrosslinking is removed and the copolymer is easy to process. Accordingto one embodiment, a specialty propylene elastomer includes at leastabout 50 mole % propylene co-monomer. Specialty propylene elastomers canalso include functional groups such as maleic anhydride, glycidyl,hydroxyl, and/or carboxylic acid. Suitable specialty propyleneelastomers include propylene-ethylene copolymers produced in thepresence of a metallocene catalyst. More specific examples of specialtypropylene elastomers are illustrated below. Specialty propyleneelastomers are commercially available under the tradename VISTAMAXX fromExxonMobil Chemical.

An especially preferred component suitable for use as additionalpolymers in the presently disclosed compositions include thepolyalkenamers. The term “polyalkenamer” is used interchangeably hereinwith the term “polyalkenamer rubber” and means a rubbery polymer of oneor more cycloalkenes having from 4-20, ring carbon atoms. Thepolyalkenamers may be prepared by ring opening metathesis polymerizationof one or more cycloalkenes in the presence of organometallic catalystsas described in U.S. Pat. Nos. 3,492,245, and 3,804,803, the entirecontents of both of which are herein incorporated by reference.

The PHPB compositions used in the golf balls of the present inventionmay also comprise a synthetic rubber comprising an injection moldablepolyalkenamer rubber. Examples of suitable polyalkenamer rubbers arepolybutenamer rubber, polypentenamer rubber, polyhexenamer rubber,polyheptenamer rubber, polyoctenamer rubber, polynonenamer rubber,polydecenamer rubber polyundecenamer rubber, polydodecenamer rubber,polytridecenamer rubber. For further details concerning polyalkenamerrubber, see Rubber Chem. & Tech., Vol. 47, page 511-596, 1974, which isincorporated herein by reference. Polyoctenamer rubbers are commerciallyavailable from Huls AG of Marl, Germany, and through its distributor inthe U.S., Creanova Inc. of Somerset, N.J., and sold under the trademarkVESTENAMER®. Two grades of the VESTENAMER® trans-polyoctenamer arecommercially available: VESTENAMER 8012 designates a material having atrans-content of approximately 80% (and a cis-content of 20%) with amelting point of approximately 54° C.; and VESTENAMER 6213 designates amaterial having a trans-content of approximately 60% (cis-content of40%) with a melting point of approximately 30° C. Both of these polymershave a double bond at every eighth carbon atom in the ring.

The polyalkenamer rubbers used in the present disclosure exhibitexcellent melt processability above their sharp melting temperatures andexhibit high miscibility with various rubber additives as a majorcomponent without deterioration of crystallinity which in turnfacilitates injection molding. Thus, unlike synthetic polybutadienerubbers typically used in golf ball core preparation, injection moldedparts of polyalkenamer-based compounds can be prepared which, inaddition, can also be partially or fully crosslinked at elevatedtemperature. The crosslinked polyalkenamer compounds are highly elastic,and their mechanical and physical properties can be easily modified byadjusting the formulation.

The polyalkenamer composition surprisingly exhibits superiorcharacteristics over a broad spectrum of properties. For example, thecompositions exhibit superior impact durability and Coefficient ofRestitution (COR) in a pre-determined hardness range (e.g., a hardnessShore D of from about 15 to about 85, preferably from about 40 to about80, and more preferably from about 40 to about 75. More particularly,the compositions disclosed herein exhibit excellent hardness adjustmentwithout significantly compromising COR or processability.

The polyalkenamer rubbers may also be blended within other polymers. Amore complete description of the various polyalkenamer rubbercompositions and blends as used in the present invention are disclosedin U.S. Pat. No. 7,528,196 and copending US Pub. No. 2009/0191981A1,U.S. Pat. No. 7,874,940 and copending US Pub. No. 2010/0323818A1 andcopending US Pub. No. 2010/0160079A1, all assigned to Taylor Made GolfCo. and all in the name of Hyun Kim at al., the entire contents of eachof which are hereby incorporated by reference.

The polyalkenamer rubber preferably contains from about 50 to about 99,preferably from about 60 to about 99, more preferably from about 65 toabout 99, even more preferably from about 70 to about 90 percent of itsdouble bonds in the trans-configuration. The preferred form of thepolyalkenamer has a trans content of approximately 80%, however,compounds having other ratios of the cis- and trans-isomeric forms ofthe polyalkenamer can also be obtained by blending available productsfor use in making the composition.

The polyalkenamer rubber has a molecular weight (as measured by GPC)from about 10,000 to about 300,000, preferably from about 20,000 toabout 250,000, more preferably from about 30,000 to about 200,000, evenmore preferably from about 50,000 to about 150,000.

The polyalkenamer rubber has a degree of crystallization (as measured byDSC secondary fusion) from about 5 to about 70, preferably from about 6to about 50, more preferably from about from 6.5 to about 50%, even morepreferably from about from 7 to about 45%,

More preferably, the polyalkenamer rubber is a polymer prepared bypolymerization of cyclooctene to form a trans-polyoctenamer rubber as amixture of linear and cyclic macromolecules.

Prior to its use in golf balls, the polyalkenamer rubber or othersynthetic rubber compositions used in the present invention may befurther formulated with one or more of the previously describedcrosslinking reagents co-crosslinking reagents, peptizers andaccelerators described above for use as a component of the crosslinkingpackage for the PHPB.

Another especially preferred component for use as an additional polymerin the presently disclosed compositions include the carboxylatedelastomers described in copending application Ser. No. 13/719,060 filedon December 18^(th), 2012 in the name of Taylor Made Golf Co., theentire contents of which are herein incorporated by reference. The termcarboxylated elastomer (CE) composition as used herein is intended tomean the family of polymers which are long chain elastomeric rubberscontaining pendant carboxyl groups at random various points along thechain as may be graphically illustrated below:

The carboxylated elastomer comprises an elastomer backbone and carboxypendant groups, wherein R may be a hydrogen, a metal (for example, analkali metal, an alkaline earth metal, or a transition metal), anammonium or a quaternary ammonium group, an acyl group (for exampleacetyl(CH₃C(O)) group), an alkyl group (such as an ester), an acidanhydride group, and combinations thereof; and R₁ may be a hydrogen, analkyl, or an aryl group. Although the pendant carboxy groups aredepicted as being in interior positions along the elastomer backbone,the carboxylated elastomer may also include terminal carboxy groupsoccurring at one or more chain ends.

One method of introducing the carboxy groups is by copolymerization of asuitable olefin monomer with a monomer comprising a carboxy group. Thefirst preparation of a carboxylic elastomer was recorded in 1933 andinvolved the copolymerization of butadiene and acrylic acid. Examples ofsuitable olefin monomers, include, but are not limited to, styrene,vinyltoluene, alpha-methylestyrene, butadiene, isoprene, hexadiene,dichlorovinylidene, vinylchloride, ethylene, propylene, butylene, andisobutylene. Examples of suitable monomers comprising a carboxy groupinclude, but are not limited to, acrylic acid, alkyacrylate, alkylalkacrylates, maleic anhydride, maleimide, acrylamide and2-acrylamido-2-methyl-1-propane sulfonic acid.

A preferred class of carboxylated elastomers for use in this inventionare the carboxylated nitrile rubbers which may be any of those known inthe art. These are copolymers of butadiene, acrylonitrile and one ormore α,μ-unsaturated carboxylic acids and which have nitrile rubber asthe elastomer backbone. A diagram of the backbone is shown below.

The carboxylic acids which are pendant to the above backbone may containone or more carboxylic groups. Because of cost and availability, it ispreferred that the carboxylic acids be selected from acrylic,methacrylic, fumaric, maleic and itaconic acids. The copolymers may beprepared by the well known emulsion free radical process. Theacrylonitrile content of the copolymer may be from about 20 to about 40percent by weight of the copolymer. The total content of carboxylic acidin the copolymer may be from about 0.5 to about 10 percent by weight ofthe copolymer. Butadiene forms the balance to 100 percent by weight ofthe copolymer. The viscosity of the copolymer is generally within theMooney range (ML 1+4 at 100° C.) of from about 40 to about 80. U.S. Pat.Nos. 4,271,052 and 4,525,517 disclose carboxylated nitrile rubbers foruse in this invention and such disclosures are incorporated herein byreference. There are a number of carboxylated elastomers that arecommercially available from Noveon under the tradename HYCAR includingHYCAR CTBN 1300X8 and CTBN 1300X8F which are a carboxyl terminatedbutadiene-acrylonitrile copolymers. HYCAR VTBNX 1300X33 which is amethacrylate terminated butadiene-acrylonitrile copolymer and HYCAR ATBN1300X16 is an amine terminated butadiene-acrylonitrile.

Another method for introducing the carboxy groups into the particularelastomer backbone is by grafting carboxy groups onto an elastomerbackbone. The elastomers may include styrene butadiene random and blockcopolymers, hydrogenated styrene butadiene random and block copolymers,acrylonitrile butadiene styrene (“ABS”) copolymers,ethylene-propylene-diene-monomer (EPDM) copolymers, styrene-acryliccopolymers, acrylonitrile butadiene rubber (NBR) polymers,methylmethacrylate butadiene styrene (MBS) rubbers, andstyrene-acrynitrile rubbers. Carboxy groups may be grafted onto ahydrophobic particulate elastomer to form a suitable graft particulateelastomer using a variety of suitable carboxylating materials,including, but not limited to, maleic acid, maleic anhydride, anddiesters and monoesters of maleic acid, maleimide, fumaric acid and itsderivatives, acrylic acid, alkylacrylate, alkylalkacrylates, acrylamide,2-acrylamido-2-methyl-1-propanesulfonic acid and its salts.

Examples of suitable graft particulate elastomers include, but are notlimited to, maleated polybutadienes, maleated styrene butadiene rubbers(“SBR”), maleated acrylonitrile-styrene-butadiene (“ABS”) rubbers,maleated nitrile-butadiene rubbers (“NBR”), maleated hydrogenatedacrylonitrile butadiene rubbers (“HNBR”), methylmethacrylate butadienestyrene (“MBS”) rubbers, carboxylated ethylene-propylene-diene monomerrubbers, carboxylated styrene-acrynitrile rubbers (“SAN”), carboxylatedethylene propylene diene rubbers (“EPDM”), acrylic grafted siliconerubbers, and combinations thereof. An example of a suitable hydrogenatedacrylonitrile butadiene rubber (“HNBR”) that is grafted withcarboxylating materials is available from Lanxess Corporation,Leverkusen, Germany, under the trade name THERBAN® XT. An example of asuitable nitrile-butadiene rubbers (“NBR”) that is grafted withcarboxylating materials is available from Zeon Chemicals, L.P.,Louisville, Ky., under the trade name NIPOL® NBR 1072 CGX. Examples ofsuitable butadiene based rubbers that are grafted with carboxylatingmaterials are available from Mitsubishi Rayon Company Ltd., Tokyo,Japan, under the trade names METABLENS® C and E. An example of anacrylic rubber that is grafted with carboxylating materials is availablefrom Mitsubishi Rayon Company Limited, Tokyo, Japan, under the tradename METABLEN® W. An example of a suitable silicone based elastomer thatis grafted with carboxylating materials is available from MitsubishiRayon America Inc., New York, N.Y., under the trade name METABLEN® S. Anexample of a suitable styrene butadiene particulate elastomer graftedwith maleic acid available as an experimental product (Eliokem XPR-100)from Eliokem Corporation.

Most preferred are the grafted polyisoprene compounds including KuraryLIR403 which is a polyisoprene-graft-maleic anhydride having thefollowing chemical structure:

Also included is Kurary LIR410 which is a polyisoprene-graft-maleicanhydride monoester of maleic anhydride having the following chemicalstructure:

where n is approximately 10, and the material has a weight averagemolecular weight of about 25,000, and a glass transition temperature of−59° C.

In addition to using directly or in blends with the PHPB to prepare thegolf ball components of the present invention, the polyalkenamers or CEcompositions may be crosslinked before or after forming into the desiredgolf ball part. When used in a blend with the PHPB, the crosslinking ofeach component may occur before or after the blending step. In view ofthe unsaturation and the pendant carboxylate functionality of the CE's,there are a number of available cross linking mechanisms which may beutilized. Given the unsaturation present in the elastomer backbone thepolyalkenamer and CE compositions are also amenable to the variousmethods used to crosslink elastomeric rubber compositions includingvulcanization, and radiation crosslinking using the same crosslinkingpackages as disclosed above for the PHPB component. Radiation can beapplied to the unsaturated polymer mixture by any known method,including using microwave or gamma radiation, or an electron beamdevice. Additives may also be used to improve radiation curing of thediene polymer. Also given the pendant carboxylate functionality of theCE's they are also amenable to the crosslinking mechanisms typicallyinvoked in ionomers via neutralization and subsequent metal ionclustering.

If a given layer in a golf ball is not the one or more comprising thePHPB composition, the cover layer and/or one or more inner cover layersof the golf ball may comprise one or more thermoplastic or thermosetpolyurethanes or polyureas. Polyurethanes or polyureas typically areprepared by reacting a diisocyanate with a polyol (in the case ofpolyurethanes) or with a polyamine (in the case of a polyurea).Thermoplastic polyurethanes or polyureas may consist solely of thisinitial mixture or may be further combined with a chain extender to varyproperties such as hardness of the thermoplastic. Thermosetpolyurethanes or polyureas typically are formed by the reaction of adiisocyanate and a polyol or polyamine respectively, and an additionalcrosslinking agent to crosslink or cure the material to result in athermoset.

In what is known as a one-shot process, the three reactants,diisocyanate, polyol or polyamine, and optionally a chain extender or acuring agent, are combined in one step. Alternatively, a two-stepprocess may occur in which the first step involves reacting thediisocyanate and the polyol (in the case of polyurethane) or thepolyamine (in the case of a polyurea) to form a so-called prepolymer, towhich can then be added either the chain extender or the curing agent.This procedure is known as the prepolymer process.

In addition, although depicted as discrete component packages as above,it is also possible to control the degree of crosslinking, and hence thedegree of thermoplastic or thermoset properties in a final composition,by varying the stoichiometry not only of the diisocyanate-to-chainextender or curing agent ratio, but also the initialdiisocyanate-to-polyol or polyamine ratio. Of course in the prepolymerprocess, the initial diisocyanate-to-polyol or polyamine ratio is fixedon selection of the required prepolymer.

Finally, in addition to discrete thermoplastic or thermoset materials,it also is possible to modify a thermoplastic polyurethane or polyureacomposition by introducing materials in the composition that undergosubsequent curing after molding the thermoplastic to provide propertiessimilar to those of a thermoset. For example, Kim in U.S. Pat. No.6,924,337, the entire contents of which are hereby incorporated byreference, discloses a thermoplastic urethane or urea compositionoptionally comprising chain extenders and further comprising a peroxideor peroxide mixture, which can then undergo post curing to result in athermoset.

Also, Kim et al. in U.S. Pat. No. 6,939,924, the entire contents ofwhich are hereby incorporated by reference, discloses a thermoplasticurethane or urea composition, optionally also comprising chainextenders, that is prepared from a diisocyanate and a modified orblocked diisocyanate which unblocks and induces further cross linkingpost extrusion. The modified isocyanate preferably is selected from thegroup consisting of: isophorone diisocyanate (IPDI)-based uretdione-typecrosslinker; a combination of a uretdione adduct of IPDI and a partiallye-caprolactam-modified IPDI; a combination of isocyanate adductsmodified by e-caprolactam and a carboxylic acid functional group; acaprolactam-modified Desmodur diisocyanate; a Desmodur diisocyanatehaving a 3,5-dimethylpyrazole modified isocyanate; or mixtures of these.

Finally, Kim et al. in U.S. Pat. No. 7,037,985 B2, the entire contentsof which are hereby incorporated by reference, discloses thermoplasticurethane or urea compositions further comprising a reaction product of anitroso compound and a diisocyanate or a polyisocyanate. The nitrosoreaction product has a characteristic temperature at which it decomposesto regenerate the nitroso compound and diisocyanate or polyisocyanate.Thus, by judicious choice of the post-processing temperature, furthercrosslinking can be induced in the originally thermoplastic compositionto provide thermoset-like properties.

In view of the advantages of injection molding versus the more complexcasting process, under some circumstances it is advantageous to haveformulations capable of curing as a thermoset but only within aspecified temperature range above that of the typical injection moldingprocess. This allows parts, such as golf ball cover layers, to beinitially injection molded, followed by subsequent processing at highertemperatures and pressures to induce further crosslinking and curing,resulting in thermoset properties in the final part. Such an initiallyinjection moldable composition is thus called a post curable urethane orurea composition.

If a post curable urethane composition is required, a modified orblocked diisocyanate which subsequently unblocks and induces furthercross linking post extrusion may be included in the diisocyanatestarting material. Modified isocyanates used for making thepolyurethanes of the present invention generally are defined as chemicalcompounds containing isocyanate groups that are not reactive at roomtemperature, but that become reactive once they reach a characteristictemperature. The resulting isocyanates can act as crosslinking agents orchain extenders to form crosslinked polyurethanes. The degree ofcrosslinking is governed by type and concentration of modifiedisocyanate presented in the composition. The modified isocyanate used inthe composition preferably is selected, in part, to have acharacteristic temperature sufficiently high such that the urethane inthe composition will retain its thermoplastic behavior during initialprocessing (such as injection molding). If a characteristic temperatureis too low, the composition crosslinks before processing is completed,leading to process difficulties. The modified isocyanate preferably isselected from isophorone diisocyanate (IPDI)-based uretdione-typecrosslinker; a combination of a uretdione adduct of IPDI and a partiallye-caprolactam-modified IPDI; a combination of isocyanate adductsmodified by e-caprolactam and a carboxylic acid functional group; acaprolactam-modified Desmodur diisocyanate; a Desmodur diisocyanatehaving a 3,5-dimethylpyrazole modified isocyanate; or mixtures of these.Particular preferred examples of modified isocyanates include thosemarketed under the trade name CRELAN by Bayer Corporation. Examples ofthese include: CRELAN TP LS 2147; CRELAN NI 2; isophorone diisocyanate(IPDI)-based uretdione-type crosslinker, such as CRELAN VP LS 2347; acombination of a uretdione adduct of IPDI and a partiallye-caprolactam-modified IPDI, such as CRELAN VP LS 2386; a combination ofisocyanate adducts modified by e-caprolactam and a carboxylic acidfunctional group, such as CRELAN VP LS 2181/1; a caprolactam-modifiedDesmodur diisocyanate, such as CRELAN NW5; and a Desmodur diisocyanatehaving a 3,5-dimethylpyrazole modified isocyanate, such as CRELAN XP7180. These modified isocyanates may be used either alone or incombination. Such modified diisocyanates are described in more detail inU.S. Pat. No. 6,939,924, the entire contents of which are herebyincorporated by reference.

As an alternative if a post curable polyurethane or polyurea compositionis required, the diisocyanate may further comprise reaction product of anitroso compound and a diisocyanate or a polyisocyanate. The reactionproduct has a characteristic temperature at which it decomposesregenerating the nitroso compound and diisocyanate or polyisocyanate,which can, by judicious choice of the post processing temperature, inturn induce further crosslinking in the originally thermoplasticcomposition resulting in thermoset-like properties. Such nitrosocompounds are described in more detail in U.S. Pat. No. 7,037,985 B2,the entire contents of which are hereby incorporated by reference.

If a given layer in a golf ball is not the one or more comprising thePHPB composition, the cover layer and/or one or more inner cover layersof the golf ball may comprise one or more ionomer resins. One family ofsuch resins was developed in the mid-1960's, by E.I. DuPont de Nemoursand Co., and sold under the trademark SURLYN®. Preparation of suchionomers is well known, for example see U.S. Pat. No. 3,264,272.Generally speaking, most commercial ionomers are unimodal and consist ofa polymer of a mono-olefin, e.g., an alkene, with an unsaturated mono-or dicarboxylic acids having 3 to 12 carbon atoms. An additional monomerin the form of a mono- or dicarboxylic acid ester may also beincorporated in the formulation as a so-called “softening comonomer”.The incorporated carboxylic acid groups are then neutralized by a basicmetal ion salt, to form the ionomer. The metal cations of the basicmetal ion salt used for neutralization include Li⁺, Na⁺, K⁺, Zn²⁺, Ca²⁺,Co²⁺, Ni²⁺, Cu²⁺, Pb²⁺, and Mg²⁺, with the Li⁺, Na⁺, Ca²⁺, Zn²⁺, andMg²⁺ being preferred. The basic metal ion salts include those of forexample formic acid, acetic acid, nitric acid, and carbonic acid,hydrogen carbonate salts, oxides, hydroxides, and alkoxides.

Today, there are a wide variety of commercially available ionomer resinsbased both on copolymers of ethylene and (meth)acrylic acid orterpolymers of ethylene and (meth)acrylic acid and (meth)acrylate, allof which can be used as a golf ball component. The properties of theseionomer resins can vary widely due to variations in acid content,softening comonomer content, the degree of neutralization, and the typeof metal ion used in the neutralization. The full range commerciallyavailable typically includes ionomers of polymers of general formula,E/X/Y polymer, wherein E is ethylene, X is a C₃ to C₈ α,β ethylenicallyunsaturated carboxylic acid, such as acrylic or methacrylic acid, and ispresent in an amount from about 0 wt. % to about 50 wt. %, particularlyabout 2 to about 30 weight %, of the E/X/Y copolymer, and Y is asoftening comonomer selected from the group consisting of alkyl acrylateand alkyl methacrylate, such as methyl acrylate or methyl methacrylate,and wherein the alkyl groups have from 1-8 carbon atoms, Y is in therange of 0 to about 50 weight %, particularly about 5 wt. % to about 35wt. %, of the E/X/Y copolymer, and wherein the acid groups present insaid ionomeric polymer are partially (e.g., about 1% to about 90%)neutralized with a metal selected from the group consisting of lithium,sodium, potassium, magnesium, calcium, barium, lead, tin, zinc oraluminum, or a combination of such cations.

The ionomer may also be a so-called bimodal ionomer as described in U.S.Pat. No. 6,562,906 (the entire contents of which are herein incorporatedby reference). These ionomers are bimodal as they are prepared fromblends comprising polymers of different molecular weights. Specificallythey include bimodal polymer blend compositions comprising:

-   -   a) a high molecular weight component having a molecular weight        of about 80,000 to about 500,000 and comprising one or more        ethylene/α,β-ethylenically unsaturated C₃₋₈ carboxylic acid        copolymers and/or one or more ethylene, alkyl(meth)acrylate,        (meth)acrylic acid terpolymers; said high molecular weight        component being partially neutralized with metal ions selected        from the group consisting of lithium, sodium, zinc, calcium,        magnesium, and a mixture of any these; and    -   b) a low molecular weight component having a molecular weight of        about from about 2,000 to about 30,000 and comprising one or        more ethylene/α,β-ethylenically unsaturated C₃₋₈ carboxylic acid        copolymers and/or one or more ethylene, alkyl(meth)acrylate,        (meth)acrylic acid terpolymers; said low molecular weight        component being partially neutralized with metal ions selected        from the group consisting of lithium, sodium, zinc, calcium,        magnesium, and a mixture of any these.

In addition to the unimodal and bimodal ionomers, also included are theso-called “modified ionomers” examples of which are described in U.S.Pat. Nos. 6,100,321, 6,329,458 and 6,616,552 and U.S. Patent PublicationNo. US 2003/0158312 A1, the entire contents of all of which are hereinincorporated by reference.

The modified unimodal ionomers may be prepared by mixing:

-   -   a) an ionomeric polymer comprising ethylene, from 5 to 25 weight        percent (meth)acrylic acid, and from 0 to 40 weight percent of a        (meth)acrylate monomer, said ionomeric polymer neutralized with        metal ions selected from the group consisting of lithium,        sodium, zinc, calcium, magnesium, and a mixture of any of these;        and    -   b) from about 5 to about 40 weight percent (based on the total        weight of said modified ionomeric polymer) of one or more fatty        acids or metal salts of said fatty acid, the metal selected from        the group consisting of calcium, sodium, zinc, potassium, and        lithium, barium and magnesium and the fatty acid preferably        being stearic acid.

The modified bimodal ionomers, which are ionomers derived from theearlier described bimodal ethylene/carboxylic acid polymers (asdescribed in U.S. Pat. No. 6,562,906, the entire contents of which areherein incorporated by reference), are prepared by mixing;

-   -   a) a high molecular weight component having a weight average        molecular weight (Mw) of about 80,000 to about 500,000 and        comprising one or more ethylene/α,β-ethylenically unsaturated        C₃₋₈ carboxylic acid copolymers and/or one or more ethylene,        alkyl(meth)acrylate, (meth)acrylic acid terpolymers; said high        molecular weight component being partially neutralized with        metal ions selected from the group consisting of lithium,        sodium, zinc, calcium, potassium, magnesium, and a mixture of        any of these; and    -   b) a low molecular weight component having a weight average        molecular weight (Mw) of about from about 2,000 to about 30,000        and comprising one or more ethylene/α,β-ethylenically        unsaturated C₃₋₈ carboxylic acid copolymers and/or one or more        ethylene, alkyl(meth)acrylate, (meth)acrylic acid terpolymers;        said low molecular weight component being partially neutralized        with metal ions selected from the group consisting of lithium,        sodium, zinc, calcium, potassium, magnesium, and a mixture of        any of these; and    -   c) from about 5 to about 40 weight percent (based on the total        weight of said modified ionomeric polymer) of one or more fatty        acids or metal salts of said fatty acid, the metal selected from        the group consisting of calcium, sodium, zinc, potassium and        lithium, barium and magnesium and the fatty acid preferably        being stearic acid.

The fatty or waxy acid salts utilized in the various modified ionomersare composed of a chain of alkyl groups containing from about 4 to 75carbon atoms (usually even numbered) and characterized by a —COOHterminal group. The generic formula for all fatty and waxy acids aboveacetic acid is CH₃(CH₂)_(X)COOH, wherein the carbon atom count includesthe carboxyl group. The fatty or waxy acids utilized to produce thefatty or waxy acid salts modifiers may be saturated or unsaturated, andthey may be present in solid, semi-solid or liquid form.

Examples of suitable saturated fatty acids, i.e., fatty acids in whichthe carbon atoms of the alkyl chain are connected by single bonds,include but are not limited to stearic acid (C₁₈, i.e., CH₃(CH₂)₁₆COOH),palmitic acid (C₁₆, i.e., CH₃(CH₂)₁₄COOH), pelargonic acid (C₉, i.e.,CH₃(CH₂)₇COOH) and lauric acid (C₁₂, i.e., CH₃(CH₂)₁₀OCOOH). Examples ofsuitable unsaturated fatty acids, i.e., a fatty acid in which there areone or more double bonds between the carbon atoms in the alkyl chain,include but are not limited to oleic acid (C₁₃, i.e.,CH₃(CH₂)₇CH:CH(CH₂)₇COOH).

The source of the metal ions used to produce the metal salts of thefatty or waxy acid salts used in the various modified ionomers aregenerally various metal salts which provide the metal ions capable ofneutralizing, to various extents, the carboxylic acid groups of thefatty acids. These include the sulfate, carbonate, acetate andhydroxylate salts of zinc, barium, calcium and magnesium.

Since the fatty acid salts modifiers comprise various combinations offatty acids neutralized with a large number of different metal ions,several different types of fatty acid salts may be utilized in theinvention, including metal stearates, laureates, oleates, andpalmitates, with calcium, zinc, sodium, lithium, potassium and magnesiumstearate being preferred, and calcium and sodium stearate being mostpreferred.

The fatty or waxy acid or metal salt of said fatty or waxy acid ispresent in the modified ionomeric polymers in an amount of from about 5to about 40, preferably from about 7 to about 35, more preferably fromabout 8 to about 20 weight percent (based on the total weight of saidmodified ionomeric polymer).

As a result of the addition of the one or more metal salts of a fatty orwaxy acid, from about 40 to 100, preferably from about 50 to 100, morepreferably from about 70 to 100 percent of the acidic groups in thefinal modified ionomeric polymer composition are neutralized by a metalion. An example of such a modified ionomer polymer is DuPont® HPF-1000available from E. I. DuPont de Nemours and Co. Inc.

If a given layer in a golf ball is not the one or more comprising thePHPB composition, the cover layer and/or one or more inner cover layersof the golf ball may comprise a blend of an ionomer and a blockcopolymer. An example of a block copolymer is a functionalized styrenicblock copolymer, the block copolymer incorporating a first polymer blockhaving an aromatic vinyl compound, a second polymer block having aconjugated diene compound in which the ratio of block copolymer toionomer ranges from 5:95 to 95:5 by weight, more preferably from about10:90 to about 90:10 by weight, more preferably from about 20:80 toabout 80:20 by weight, more preferably from about 30:70 to about 70:30by weight and most preferably from about 35:65 to about 65:35 by weight.A preferred block copolymer is SEPTON HG-252. Such blends are describedin more detail in commonly-assigned U.S. Pat. No. 6,861,474 and U.S.Patent Publication No. 2003/0224871 both of which are incorporatedherein by reference in their entireties.

Another preferred material to which the PHPB may be added and which alsomay be used as a separate component of the cover layer or intermediatelayer of the golf balls of the present invention is a multi-componentblend composition (“MCBC”) prepared by blending together at least threematerials, identified as Components A, B, and C, and melt-processingthese components to form in-situ, a polymer blend compositionincorporating a pseudo-crosslinked polymer network. Such blends are morefully described in U.S. Pat. No. 6,930,150 to H. J. Kim, the entirecontents of which are hereby incorporated by reference.

The first of these blend components (blend Component A) include blockcopolymers including di and triblock copolymers, incorporating a firstpolymer block having an aromatic vinyl compound, and a second polymerblock having an olefinic and/or conjugated diene compound. Preferredaromatic vinyl compounds include styrene, α-methylstyrene, o-, m- orp-methylstyrene, 4-propylstyrene, 1,3-dimethylstyrene, vinylnaphthaleneand vinylanthracene. In particular, styrene and α-methylstyrene arepreferred. These aromatic vinyl compounds can each be used alone, or canbe used in combination of two or more kinds. The aromatic vinyl compoundis preferably contained in the block copolymer (b) in an amount of from5 to 75% by weight, and more preferably from 10 to 65% by weight.

The conjugated diene compound, that constitutes the polymer block B inthe block copolymer (b), includes, e.g., 1,3-butadiene, isoprene,2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and 1,3-hexadiene. Inparticular, isoprene and 1,3-butadiene are preferred. These conjugateddiene compounds can each be used alone, or can be used in combination oftwo or more kinds.

Preferred block copolymers include the styrenic block copolymers such asstyrene-butadiene-styrene (SBS), styrene-ethylene-butylene-styrene,(SEBS) and styrene-ethylene-propylene-styrene (SEPS). Commercialexamples include SEPTON marketed by Kuraray Company of Kurashiki, Japan;TOPRENE by Kumho Petrochemical Co., Ltd and KRATON marketed by KratonPolymers.

Also included are functionalized styrenic block copolymers, includingthose where the block copolymer incorporates a first polymer blockhaving an aromatic vinyl compound, a second polymer block having aconjugated diene compound and a hydroxyl group located at a blockcopolymer, or its hydrogenation product. A preferred functionalizedstyrenic block copolymer is SEPTON HG-252.

The second blend component, Component B, is an acidic polymer thatincorporates at least one type of an acidic functional group. Examplesof such polymers suitable for use as include, but are not limited to,ethylene/(meth)acrylic acid copolymers and ethylene/(meth)acrylicacid/alkyl(meth)acrylate terpolymers, or ethylene and/or propylenemaleic anhydride copolymers and terpolymers. Examples of such polymerswhich are commercially available include, but are not limited to, theEscor® 5000, 5001, 5020, 5050, 5070, 5100, 5110 and 5200 series ofethylene-acrylic acid copolymers sold by Exxon Mobil, the PRIMACOR®1321, 1410, 1410-XT, 1420, 1430, 2912, 3150, 3330, 3340, 3440, 3460,4311, 4608 and 5980 series of ethylene-acrylic acid copolymers sold byThe Dow Chemical Company, Midland, Mich. and the ethylene-methacrylicacid copolymers such as Nucrel 599, 699, 0903, 0910, 925, 960, 2806, and2906 commercially available from DuPont

Also included are the so called bimodal ethylene/carboxylic acidpolymers as described in U.S. Pat. No. 6,562,906, the contents of whichare incorporated herein by reference. These polymers comprise a firstcomponent comprising an ethylene/α,β-ethylenically unsaturated C₃₋₈carboxylic acid high copolymer, particularly ethylene(meth)acrylic acidcopolymers and ethylene, alkyl(meth)acrylate, (meth)acrylic acidterpolymers, having a weight average molecular weight, Mw, of about80,000 to about 500,000, and a second component comprising anethylene/α,β-ethylenically unsaturated C₃₋₈ carboxylic acid copolymers,particularly ethylene/(meth)acrylic acid copolymers having weightaverage molecular weight, Mw, of about 2,000 to about 30,000.

Component C is a base capable of neutralizing the acidic functionalgroup of Component B and typically is a base having a metal cation.These metals are from groups IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA,VB, VIA, VIB, VIIB and VIIIB of the periodic table. Examples of thesemetals include lithium, sodium, magnesium, aluminum, potassium, calcium,manganese, tungsten, titanium, iron, cobalt, nickel, hafnium, copper,zinc, barium, zirconium, and tin. Suitable metal compounds for use as asource of Component C are, for example, metal salts, preferably metalhydroxides, metal oxides, metal carbonates, metal acetates, metalstearates, metal laureates, metal oleates, metal palmitates and thelike.

The MCBC composition preferably is prepared by mixing the abovematerials into each other thoroughly, either by using a dispersivemixing mechanism, a distributive mixing mechanism, or a combination ofthese. These mixing methods are well known in the manufacture of polymerblends. As a result of this mixing, the acidic functional group ofComponent B is dispersed evenly throughout the mixture in either theirneutralized or non-neutralized state. Most preferably, Components A andB are melt-mixed together without Component C, with or without thepremixing discussed above, to produce a melt-mixture of the twocomponents. Then, Component C separately is mixed into the blend ofComponents A and B. This mixture is melt-mixed to produce the reactionproduct. This two-step mixing can be performed in a single process, suchas, for example, an extrusion process using a proper barrel length orscrew configuration, along with a multiple feeding system.

The PHPB and the various other polymer compositions used to preparecore, mantle or outer cove layers of the golf balls of the presentinvention may also incorporate one or more fillers. Such fillers aretypically in a finely divided form, for example, in a size generallyless than about 20 mesh, preferably less than about 100 mesh U.S.standard size, except for fibers and flock, which are generallyelongated. Flock and fiber sizes should be small enough to facilitateprocessing. Filler particle size will depend upon desired effect, cost,ease of addition, and dusting considerations. The appropriate amounts offiller required will vary depending on the application but typically canbe readily determined without undue experimentation.

The filler preferably is selected from the group consisting ofprecipitated hydrated silica, limestone, clay, talc, asbestos, barytes,glass fibers, aramid fibers, mica, calcium metasilicate, barium sulfate,zinc sulfide, lithopone, silicates, silicon carbide, diatomaceous earth,carbonates such as calcium or magnesium or barium carbonate, sulfatessuch as calcium or magnesium or barium sulfate, metals, includingtungsten steel copper, cobalt or iron, metal alloys, tungsten carbide,metal oxides, metal stearates, and other particulate carbonaceousmaterials, and any and all combinations thereof. Preferred examples offillers include metal oxides, such as zinc oxide and magnesium oxide. Inanother preferred embodiment the filler comprises a continuous ornon-continuous fiber.

In another preferred embodiment the filler comprises one or more socalled nanofillers, as described in U.S. Pat. No. 6,794,447 andcopending U.S. Publication No. US2004-0092336 filed on Sep. 24, 2003 andU.S. Pat. No. 7,332,533 filed on Aug. 25, 2004, the entire contents ofeach of which are incorporated herein by reference. Examples ofcommercial nanofillers are various Cloisite grades including 10A, 15A,20A, 25A, 30B, and NA+ of Southern Clay Products (Gonzales, Tex.) andthe Nanomer grades including 1.24TL and C.30EVA of Nanocor, Inc.(Arlington Heights, Ill.).

Materials incorporating nanofiller materials can provide these propertyimprovements at much lower densities than those incorporatingconventional fillers. For example, a nylon-6 nanocomposite materialmanufactured by RTP Corporation of Wichita, Kans. uses a 3% to 5% clayloading and has a tensile strength of 11,800 psi and a specific gravityof 1.14, while a conventional 30% mineral-filled material has a tensilestrength of 8,000 psi and a specific gravity of 1.36. Because use ofnanocomposite materials with lower loadings of inorganic materials thanconventional fillers provides the same properties, this use allowsproducts to be lighter than those with conventional fillers, whilemaintaining those same properties.

As used herein, a “nanocomposite” is defined as a polymer matrix havingnanofiller intercalated or exfoliated within the matrix. Physicalproperties of the polymer will change with the addition of nanofillerand the physical properties of the polymer are expected to improve evenmore as the nanofiller is dispersed into the polymer matrix to form ananocomposite.

Nanocomposite materials are materials incorporating from about 0.1% toabout 20%, preferably from about 0.1% to about 15%, and most preferablyfrom about 0.1% to about 10% of nanofiller reacted into andsubstantially dispersed through intercalation or exfoliation into thestructure of an organic material, such as a polymer, to providestrength, temperature resistance, and other property improvements to theresulting composite. Descriptions of particular nanocomposite materialsand their manufacture can be found in U.S. Pat. No. 5,962,553 toEllsworth, U.S. Pat. No. 5,385,776 to Maxfield et al., and U.S. Pat. No.4,894,411 to Okada et al. Examples of nanocomposite materials currentlymarketed include M1030D, manufactured by Unitika Limited, of Osaka,Japan, and 1015C2, manufactured by UBE America of New York, N.Y.

Preferably the nanofiller material is added to the polymeric compositionin an amount of from about 0.1% to about 20%, preferably from about 0.1%to about 15%, and most preferably from about 0.1% to about 10% by weightof nanofiller reacted into and substantially dispersed throughintercalation or exfoliation into the structure of the polymericcomposition.

If desired, the various polymer compositions used to prepare the golfballs can additionally contain other additives such as plasticizers,pigments, antioxidants, U.V. absorbers, optical brighteners, or anyother additives generally employed in plastics formulation or thepreparation of golf balls.

Another particularly well-suited additive for use in the presentlydisclosed compositions includes compounds having the general formula:

(R₂N)_(m)—R′—(X(O)_(n)OR_(y))_(m),

where R is hydrogen, or a C1-C20 aliphatic, cycloaliphatic or aromaticsystems; R′ is a bridging group comprising one or more C₁-C₂₀ straightchain or branched aliphatic or alicyclic groups, or substituted straightchain or branched aliphatic or alicyclic groups, or aromatic group, oran oligomer of up to 12 repeating units including, but not limited to,polypeptides derived from an amino acid sequence of up to 12 aminoacids; and X is C or S or P with the proviso that when X=C, n=1 and y=1and when X=S, n=2 and y=1, and when X=P, n=2 and y=2. Also, m=1-3. Thesematerials are more fully described in copending U.S. Provisional PatentApplication No. 60/588,603, filed on Jul. 16, 2004, the entire contentsof which are herein incorporated by reference. These materials includecaprolactam, oenantholactam, decanolactam, undecanolactam,dodecanolactam, caproic 6-amino acid, 11-aminoundecanoicacid,12-aminododecanoic acid, diamine hexamethylene salts of adipic acid,azeleic acid, sebacic acid and 1,12-dodecanoic acid and the diaminenonamethylene salt of adipic acid., 2-aminocinnamic acid, L-asparticacid, 5-aminosalicylic acid, aminobutyric acid; aminocaproic acid;aminocapyryic acid; 1-(aminocarbonyl)-1-cyclopropanecarboxylic acid;aminocephalosporanic acid; aminobenzoic acid; aminochlorobenzoic acid;2-(3-amino-4-chlorobenzoyl)benzoic acid; aminonaphtoic acid;aminonicotinic acid; aminonorbornanecarboxylic acid; aminoorotic acid;aminopenicillanic acid; aminopentenoic acid; (aminophenyl)butyric acid;aminophenyl propionic acid; aminophthalic acid; aminofolic acid;aminopyrazine carboxylic acid; aminopyrazole carboxylic acid;aminosalicylic acid; aminoterephthalic acid; aminovaleric acid; ammoniumhydrogencitrate; anthranillic acid; aminobenzophenone carboxylic acid;aminosuccinamic acid, epsilon-caprolactam; omega-caprolactam,(carbamoylphenoxy)acetic acid, sodium salt; carbobenzyloxy asparticacid; carbobenzyl glutamine; carbobenzyloxyglycine; 2-aminoethylhydrogensulfate; aminonaphthalenesulfonic acid; aminotoluene sulfonicacid; 4,4′-methylene-bis-(cyclohexylamine)carbamate and ammoniumcarbamate.

Most preferably the material is selected from the group consisting of4,4′-methylene-bis-(cyclohexylamine)carbamate (commercially availablefrom R.T. Vanderbilt Co., Norwalk, Conn. under the tradename Diak® 4),11-aminoundecanoicacid, 12-aminododecanoic acid, epsilon-caprolactam;omega-caprolactam, and any and all combinations thereof.

In an especially preferred embodiment a nanofiller additive component inthe golf ball is surface modified with a compatibilizing agentcomprising the earlier described compounds having the general formula:

(R₂N)_(m)—R′—(X(O)_(n)OR_(y))_(m),

A most preferred embodiment would be a filler comprising a nanofillerclay material surface modified with an amino acid including12-aminododecanoic acid. Such fillers are available from Nanonocor Co.under the tradename Nanomer 1.24TL. Disclosed compositions havesufficient shear-cut resistance and excellent mechanical properties thatmake them suitable for making sports equipment, such as a recreationball, a golf club or component thereof, such as a grip, shoes, glove,helmet, protective gears, bicycle, football, soccer, basketball,baseball, volley ball, hockey, ski, skate and the like.

In addition to the PHPB rubber, the cores of the golf balls of thepresent invention may include the traditional rubber components used ingolf ball applications including, both natural and synthetic rubbers,such as cis-1,4-polybutadiene, trans-1,4-polybutadiene,1,2-polybutadiene, cis-polyisoprene, trans-polyisoprene,polychloroprene, polybutylene, styrene-butadiene rubber,styrene-butadiene-styrene block copolymer and partially and fullyhydrogenated equivalents, styrene-isoprene-styrene block copolymer andpartially and fully hydrogenated equivalents, nitrile rubber, siliconerubber, and polyurethane, as well as mixtures of these. Polybutadienerubbers, especially 1,4-polybutadiene rubbers containing at least 40 mol%, and more preferably 80 to 100 mol % of cis-1,4 bonds, are preferredbecause of their high rebound resilience, moldability, and high strengthafter vulcanization. The polybutadiene component may be synthesized byusing rare earth-based catalysts, nickel-based catalysts, orcobalt-based catalysts, conventionally used in this field. Polybutadieneobtained by using lanthanum rare earth-based catalysts usually employ acombination of a lanthanum rare earth (atomic number of 57 to71)-compound, but particularly preferred is a neodymium compound.

The 1,4-polybutadiene rubbers have a molecular weight distribution(Mw/Mn) of from about 1.2 to about 4.0, preferably from about 1.7 toabout 3.7, even more preferably from about 2.0 to about 3.5, mostpreferably from about 2.2 to about 3.2. The polybutadiene rubbers have aMooney viscosity (ML₁₊₄ (100° C.)) of from about 20 to about 80,preferably from about 30 to about 70, even more preferably from about 30to about 60, most preferably from about 35 to about 50. The term “Mooneyviscosity” used herein refers in each case to an industrial index ofviscosity as measured with a Mooney viscometer, which is a type ofrotary plastometer (see JIS K6300). This value is represented by thesymbol ML₁₊₄ (100° C.), wherein “M” stands for Mooney viscosity, “L”stands for large rotor (L-type), “1+4” stands for a pre-heating time of1 minute and a rotor rotation time of 4 minutes, and “100° C.” indicatesthat measurement was carried out at a temperature of 100° C. As readilyappreciated by one skilled in the art, blends of polybutadiene rubbersmay also be utilized in the golf balls of the present invention, suchblends may be prepared with any mixture of rare earth-based catalysts,nickel-based catalysts, or cobalt-based catalysts derived materials, andfrom materials having different molecular weights, molecular weightdistributions and Mooney viscosity.

The cores of the golf balls of the present invention may also include1,2-polybutadienes having differing tacticity, all of which are suitableas unsaturated polymers for use in the presently disclosed compositions,are atactic 1,2-polybutadiene, isotactic 1,2-polybutadiene, andsyndiotactic 1,2-polybutadiene. Syndiotactic 1,2-polybutadiene havingcrystallinity suitable for use as an unsaturated polymer in thepresently disclosed compositions are polymerized from a 1,2-addition ofbutadiene. The presently disclosed golf balls may include syndiotactic1,2-polybutadiene having crystallinity and greater than about 70% of1,2-bonds, more preferably greater than about 80% of 1,2-bonds, and mostpreferably greater than about 90% of 1,2-bonds. Also, the1,2-polybutadiene may have a mean molecular weight between about 10,000and about 350,000, more preferably between about 50,000 and about300,000, more preferably between about 80,000 and about 200,000, andmost preferably between about 10,000 and about 150,000. Examples ofsuitable syndiotactic 1,2-polybutadienes having crystallinity suitablefor use in golf balls are sold under the trade names RB810, RB820, andRB830 by JSR Corporation of Tokyo, Japan.

The cores of the golf balls of the present invention may also includethe polyalkenamer rubbers as previously described herein and disclosedin U.S. Pat. No. 7,528,196 in the name of Hyun Kim et al., the entirecontents of which are hereby incorporated by reference.

When synthetic rubbers such as the aforementioned polybutadienes orpolyalkenamers and their blends are used in the golf balls of thepresent invention they may contain further materials typically oftenused in rubber formulations including crosslinking agents,co-crosslinking agents, peptizers and accelerators, all of which methodsand amounts are described above for crosslinking the carboxylatedelastomers.

Typically the golf ball core is made by mixing together the unsaturatedpolymer, cross-linking agents, and other additives with or withoutmelting them. Dry blending equipment, such as a tumbler mixer, Vblender, ribbon blender, or two-roll mill, can be used to mix thecompositions. The golf ball core compositions can also be mixed using amill, internal mixer such as a Banbury or Farrel continuous mixer,extruder or combinations of these, with or without application ofthermal energy to produce melting. The various core components can bemixed together with the cross-linking agents, or each additive can beadded in an appropriate sequence to the milled unsaturated polymer. Inanother method of manufacture the cross-linking agents and othercomponents can be added to the unsaturated polymer as part of aconcentrate using dry blending, roll milling, or melt mixing. Ifradiation is a cross-linking agent, then the mixture comprising theunsaturated polymer and other additives can be irradiated followingmixing, during forming into a part such as the core of a ball, or afterforming.

The resulting mixture can be subjected to, for example, a compression orinjection molding process, to obtain solid spheres for the core. Thepolymer mixture is subjected to a molding cycle in which heat andpressure are applied while the mixture is confined within a mold. Thecavity shape depends on the portion of the golf ball being formed. Thecompression and heat liberates free radicals by decomposing one or moreperoxides, which initiate cross-linking. The temperature and duration ofthe molding cycle are selected based upon the type of peroxide andpeptizer selected. The molding cycle may have a single step of moldingthe mixture at a single temperature for fixed time duration.

For example, a preferred mode of preparation for the cores used in thepresent invention is to first mix the core ingredients on a two-rollmill, to form slugs of approximately 30-40 g, and then compression-moldin a single step at a temperature between 150 to 180° C., for a timeduration between 5 and 12 minutes.

The various core components may also be combined to form a golf ball byan injection molding process, which is also well known to one ofordinary skill in the art. The curing time depends on the variousmaterials selected, and those of ordinary skill in the art will bereadily able to adjust the curing time upward or downward based on theparticular materials used and the discussion herein.

The various formulations for the intermediate layer and/or outer coverlayer may be produced by any generally known method, such as dryblending, melt-mixing, or combination of those, to achieve a gooddispersive mixing, distributive mixing, or both. Examples of melt-mixingare roll-mill; internal mixer, such as injection molding, single-screwextruder, twin-screw extruder; or any combination of those The feed tothe injection mold may be blended manually or mechanically prior to theaddition to the injection molder feed hopper. Finished golf balls may beprepared by initially positioning the solid, preformed core in aninjection-molding cavity, followed by uniform injection of theintermediate layer and/or cover layer composition sequentially over thecore. The cover formulations can be injection molded around the cores toproduce golf balls of the required diameter.

Alternatively, the intermediate layers and/or outer cover layer may alsobe formed around the core by first forming half shells by injectionmolding followed by compression molding the half shells about the coreto form the final ball.

The intermediate layers and/or outer cover layer may also be formedaround the cores using compression molding. Cover materials forcompression molding may also be extruded or blended resins or castableresins such as thermoset polyurethane or thermoset polyurea.

The polybutadiene to be hydrogenated to form the PHPB for use in thegolf ball of the present invention may contain of from about 20 to about80 preferably of from about 30 to about 70, and more preferably of fromabout 45 to about 65 mol percent trans 1,4-addition. The polybutadieneto be hydrogenated to form the PHPB for use in the golf ball of thepresent invention may contain of from about 10 to about 70, preferablyof from about 20 to about 60, and more preferably of from about andabout 25 to about 45 mole percent cis 1,4-addition. The remainder of thepolymer is formed by 1,2-addition of the 1,3-butadiene to give the 1,2vinyl content.

The weight average molecular weight of the polybutadiene to behydrogenated to form the PHPB product is in the range of from about50,000 to about 300,000, preferably of from about 75,000 to about250,000, even more preferably of from about 90,000 to about 200,000.

The degree of hydrogenation of the PHPB is carried out to such a degreethat of from about 25 to about 75, preferably of from about 30 to about70, more preferably of from about 35 to about 65 and even morepreferably of from about 40 to about 60% of the double bonds in theoriginal polybutadiene have been hydrogenated and are thus saturated.

In one preferred aspect the PHPB or PHPB-containing blend material usedin the present invention may be crosslinked using a compositioncomprising one or more peroxides in a total amount of from about 0.1 toabout 5, preferably of from about 0.5 to about 3, and more preferably offrom about 0.75 to about 1.5 pph based on the total weight of PHPB.

The crosslinking composition also comprises at least one zinc ormagnesium salt of an unsaturated fatty acids having 3 to 8 carbon atomsselected from the group consisting of acrylic acid, methacrylic acid,maleic acid, stearic acid, fumaric acid, palmitic acid and mixturesthereof present in an amount of from about less than about 150,preferably less than about 125, and more preferably less than about 100pph and more preferably of from about 5 to about 100 pph based on thetotal weight of PHPB.

This mechanism is known as free radical crosslinking. When used in ablend composition the PHPB may be crosslinked by this crosslinkingpackage before or after its incorporation into the blend composition

The PHPB compositions or PHPB-containing blend compositions used in thegolf balls of the present invention may comprise from about 2 to about100, preferably from about 5 to about 95 and more preferably from about10 to about 90 and most preferably from about 20 to about 80 wt % of thePHPB and from about 0 to about 98, preferably from about 5 to about 95and more preferably from about 10 to about 90 and most preferably fromabout 20 to about 80 wt % of one or more additional polymer components(all wt % based on the total weight of PHPB and additional polymercomponent(s)).

The PHPB or PHPB-containing blend material has a Melt Flow Index (MFI)of from about 1 to about 80, preferably of from about 4 to about 60,more preferably of from about 5 to about 50 and most preferably of fromabout 10 to about 30 g/10 min.

The PHPB or PHPB-containing blend material has a material hardness offrom about 20 to about 90, preferably of from about 25 to about 85 morepreferably of from about 30 to about 80 and most preferably of fromabout 35 to about 70 Shore D.

The PHPB or PHPB-containing blend material has a flex modulus of fromabout 1 to about 120, preferably of from about 2 to about 100, morepreferably of from about 3 to about 90 and most preferably of from about4 to about 70 kpsi.

The golf ball of the present invention comprises a core and may comprisefrom 0 to 6, preferably from 0 to 5, more preferably from about 1 toabout 4, most preferably from about 1 to about 3 intermediate or mantlelayer(s).

In one preferred aspect, the golf ball is a two-piece ball with the PHPBor PHPB-containing blend composition used in the outer cover layer.

In one preferred aspect, the golf ball is a multi-piece ball wherein theouter cover comprises the PHPB or PHPB-containing blend materialdescribed herein.

In one preferred aspect, the golf ball is a multi-piece ball having atleast one intermediate or mantle layer which comprises the PHPB orPHPB-containing blend material described herein.

In another preferred aspect the golf ball is a three-piece ball with aunitary core and the outer cover layer comprises the PHPB orPHPB-containing blend material and the intermediate or mantle layercomprises a block copolymer, an acidic polymer, a unimodal ionomer, abimodal ionomer, a modified unimodal ionomer, a modified bimodalionomer, a polyalkenamer, a polyamide, a thermoplastic or thermosetpolyurethane or thermoplastic or thermoset polyurea, or a multicomponentblend composition (“MCBC”), the MCBC comprising (A) a block copolymer;and (B) one or more acidic polymers; and (C) one or more basic metalsalts present in an amount to neutralize at greater than or equal toabout 30 percent of the acid groups of Component (B), and any and allcombinations thereof.

In another aspect the golf ball is a four-piece ball with a unitary coreand the outer cover layer comprises the PHPB or PHPB-containing blendmaterial and one or both of the inner and outer intermediate layerscomprises a block copolymer, an acidic polymer, a unimodal ionomer, abimodal ionomer, a modified unimodal ionomer, a modified bimodalionomer, a polyalkenamer, a polyamide, a thermoplastic or thermosetpolyurethane or thermoplastic or thermoset polyurea, or a multicomponentblend composition (“MCBC”), the MCBC comprising (A) a block copolymer;and (B) one or more acidic polymers; and (C) one or more basic metalsalts present in an amount to neutralize at greater than or equal toabout 30 percent of the acid groups of Component (B), and any and allcombinations thereof.

In another aspect the golf ball is a five-piece ball with a unitary coreand the outer cover layer comprises the PHPB or PHPB-containing blendmaterial and one or more of the three intermediate or mantle layerscomprises a block copolymer, an acidic polymer, a unimodal ionomer, abimodal ionomer, a modified unimodal ionomer, a modified bimodalionomer, a polyalkenamer, a polyamide, a thermoplastic or thermosetpolyurethane or thermoplastic or thermoset polyurea, or a multicomponentblend composition (“MCBC”), the MCBC comprising (A) a block copolymer;and (B) one or more acidic polymers; and (C) one or more basic metalsalts present in an amount to neutralize at greater than or equal toabout 30 percent of the acid groups of Component (B), and any and allcombinations thereof.

In another aspect the golf ball is a six-piece ball with a unitary coreand the outer cover layer comprises the PHPB or PHPB-containing blendmaterial and one or more of the four intermediate or mantle layerscomprises a block copolymer, an acidic polymer, a unimodal ionomer, abimodal ionomer, a modified unimodal ionomer, a modified bimodalionomer, a polyalkenamer, a polyamide, a thermoplastic or thermosetpolyurethane or thermoplastic or thermoset polyurea, or a multicomponentblend composition (“MCBC”), the MCBC comprising (A) a block copolymer;and (B) one or more acidic polymers; and (C) one or more basic metalsalts present in an amount to neutralize at greater than or equal toabout 30 percent of the acid groups of Component (B), and any and allcombinations thereof.

In another aspect the golf ball is a three-piece ball with theintermediate or mantle layer comprising the PHPB or PHPB-containingblend material and the outer cover layer comprises a block copolymer, anacidic polymer, a unimodal ionomer, a bimodal ionomer, a modifiedunimodal ionomer, a modified bimodal ionomer, a polyalkenamer, apolyamide, a thermoplastic or thermoset polyurethane or thermoplastic orthermoset polyurea, or a multicomponent blend composition (“MCBC”), theMCBC comprising (A) a block copolymer; and (B) one or more acidicpolymers; and (C) one or more basic metal salts present in an amount toneutralize at greater than or equal to about 30 percent of the acidgroups of Component (B), and any and all combinations thereof.

In another aspect the golf ball is a four-piece ball with a unitary coreand one or both of the inner and outer intermediate layer comprises thePHPB or PHPB-containing blend material and the outer cover layercomprises a block copolymer, an acidic polymer, a unimodal ionomer, abimodal ionomer, a modified unimodal ionomer, a modified bimodalionomer, a polyalkenamer, a polyamide, a thermoplastic or thermosetpolyurethane or thermoplastic or thermoset polyurea, or a multicomponentblend composition (“MCBC”), the MCBC comprising (A) a block copolymer;and (B) one or more acidic polymers; and (C) one or more basic metalsalts present in an amount to neutralize at greater than or equal toabout 30 percent of the acid groups of Component (B), and any and allcombinations thereof.

In another aspect the golf ball is a five-piece ball with a unitary coreand one or more of the three intermediate or mantle layers comprises thePHPB or PHPB-containing blend material and the outer cover layercomprises a block copolymer, an acidic polymer, a unimodal ionomer, abimodal ionomer, a modified unimodal ionomer, a modified bimodalionomer, a polyalkenamer, a polyamide, a thermoplastic or thermosetpolyurethane or thermoplastic or thermoset polyurea, or a multicomponentblend composition (“MCBC”), the MCBC comprising (A) a block copolymer;and (B) one or more acidic polymers; and (C) one or more basic metalsalts present in an amount to neutralize at greater than or equal toabout 30 percent of the acid groups of Component (B), and any and allcombinations thereof.

In another aspect the golf ball is a six-piece ball with a unitary coreand the one or more of the four intermediate or mantle layers comprisesthe PHPB or PHPB-containing blend material and the outer cover layercomprises a block copolymer, an acidic polymer, a unimodal ionomer, abimodal ionomer, a modified unimodal ionomer, a modified bimodalionomer, a polyalkenamer, a polyamide, a thermoplastic or thermosetpolyurethane or thermoplastic or thermoset polyurea, or a multicomponentblend composition (“MCBC”), the MCBC comprising (A) a block copolymer;and (B) one or more acidic polymers; and (C) one or more basic metalsalts present in an amount to neutralize at greater than or equal toabout 30 percent of the acid groups of Component (B), and any and allcombinations thereof.

The one or more intermediate layers of the golf balls may have athickness of from about 0.010 to about 0.400, preferably from about0.020 to about 0.200 and most preferably from about 0.030 to about 0.100inches.

The one or more intermediate layers of the golf balls may also have aShore D hardness as measured on the ball of greater than about 25,preferably greater than about 40, and most preferably greater than about50 Shore D units.

The outer cover layer of the balls may have a thickness of from about0.015 to about 0.100, preferably from about 0.020 to about 0.080, morepreferably from about 0.025 to about 0.060 inches.

The outer cover layer the balls may also have a Shore D hardness asmeasured on the ball of from about 30 to about 75, preferably from 38 toabout 68 and most preferably from about 40 to about 65.

The core of the balls also may have a PGA compression of less than about140, preferably less than about 100, and most preferably less than about90.

The various core layers (including the center) if present may eachexhibit a different hardness. The difference between the center hardnessand that of the next adjacent layer, as well as the difference inhardness between the various core layers may be greater than 2,preferably greater than 5, most preferably greater than 10 units ofShore D.

In one preferred aspect, the hardness of the center and each sequentiallayer increases progressively outwards from the center to outer corelayer.

In another preferred aspect, the hardness of the center and eachsequential layer decreases progressively inwards from the outer corelayer to the center.

The core of the balls may have a diameter of from about 0.5 to about1.62, preferably from about 0.7 to about 1.60, more preferably fromabout 0.9 to about 1.58, yet more preferably from about 1.20 to about1.54, and even more preferably from about 1.40 to about 1.50 in.

More specifically, for a three piece golf ball consisting of a core, amantle, and a cover, the diameter of the core is most preferably greaterthan or equal to 1.41 inches in diameter.

More specifically, for a four piece golf ball (consisting of a core, aninner mantle, an outer mantle, and a cover wherein the inner mantle isencased by an outer mantle) the diameter of the core is most preferablygreater than or equal to 1.00 inches in diameter.

More specifically, for a five piece golf ball (consisting of an innercore, an outer core, an inner mantle, an outer mantle, and a coverwherein the inner core and inner mantle are encased by outer core andouter mantle, respectively) the diameter of the core is most preferablygreater than or equal to 1.00 inches in diameter.

More specifically, for a six piece golf ball (consisting of an innercore, an intermediate core, an outer core, an inner mantle, an outermantle, and a cover wherein the intermediate core and inner mantle areencased by outer core and outer mantle, respectively) the diameter ofthe core is most preferably greater than or equal to 1.00 inches indiameter.

More specifically, for a six piece golf ball (consisting of an innercore, an outer core, an inner mantle, an intermediate mantle, an outermantle, and a cover wherein the intermediate core and inner mantle areencased by outer core and outer mantle, respectively) the diameter ofthe core is most preferably greater than or equal to 1.00 inches indiameter.

The COR of the golf balls may be greater than about 0.700, preferablygreater than about 0.730, more preferably greater than 0.750, mostpreferably greater than 0.775, and especially greater than 0.800 at 125ft/sec inbound velocity.

The shear cut resistance of the golf balls of the present invention isless than about 4, preferably less than about 3, even more preferablyless than about 2.

These and other aspects of the present invention may be more fullyunderstood by reference to the following examples. While these examplesare meant to be illustrative of golf balls and golf ball components madeaccording to the present invention, the present invention is not meantto be limited by the following examples.

EXAMPLES

The various test properties which may be used to measure the propertiesof the golf balls of the present invention are described below includingany test methods as defined below.

Core or ball diameter may be determined by using standard linearcalipers or size gauge.

Compression may be measured by applying a spring-loaded force to thegolf ball center, golf ball core, or the golf ball to be examined, witha manual instrument (an “Atti gauge”) manufactured by the AttiEngineering Company of Union City, N.J. This machine, equipped with aFederal Dial Gauge, Model D81-C, employs a calibrated spring under aknown load. The sphere to be tested is forced a distance of 0.2 inch (5mm) against this spring. If the spring, in turn, compresses 0.2 inch,the compression is rated at 100; if the spring compresses 0.1 inch, thecompression value is rated as 0. Thus more compressible, softermaterials will have lower Atti gauge values than harder, lesscompressible materials. Compression measured with this instrument isalso referred to as PGA compression. The approximate relationship thatexists between Atti or PGA compression and Riehle compression can beexpressed as:

(Atti or PGA compression)=(160−Riehle Compression).

Thus, a Riehle compression of 100 would be the same as an Atticompression of 60.

COR may be measured using a golf ball or golf ball subassembly, aircannon, and a stationary steel plate. The steel plate provides an impactsurface weighing about 100 pounds or about 45 kilograms. A pair ofballistic light screens, which measure ball velocity, are spaced apartand located between the air cannon and the steel plate. The ball isfired from the air cannon toward the steel plate over a range of testvelocities from 50 ft/s to 180 ft/sec (for the tests used herein thevelocity was 125 ft/sec). As the ball travels toward the steel plate, itactivates each light screen so that the time at each light screen ismeasured. This provides an incoming time period proportional to theball's incoming velocity. The ball impacts the steel plate and reboundsthough the light screens, which again measure the time period requiredto transit between the light screens. This provides an outgoing transittime period proportional to the ball's outgoing velocity. Thecoefficient of restitution can be calculated by the ratio of theoutgoing transit time period to the incoming transit time period,COR=T_(out)/T_(in).

A “Mooney” viscosity is a unit used to measure the plasticity of raw orunvulcanized rubber. The plasticity in a Mooney unit is equal to thetorque, measured on an arbitrary scale, on a disk in a vessel thatcontains rubber at a temperature of 100° C. and rotates at tworevolutions per minute. The measurement of Mooney viscosity is definedaccording to ASTM D-1646.

Shore D hardness may be measured in accordance with ASTM Test D2240.

Melt flow index (MFI, I2) may be measured in accordance with ASTMD-1238, Condition 230° C./2.16 kg.

Tensile Strength and Tensile Elongation were measured with ASTM D-638.

Flexural modulus and flexural strength were measured using ASTM standardD-790.

Shear cut resistance may be determined by examining the balls after theywere impacted by a pitching wedge at controlled speed, classifying eachnumerically from 1 (excellent) to 5 (poor), and averaging the resultsfor a given ball type. Three samples of each Example may be used forthis testing. Each ball is hit twice, to collect two impact data pointsper ball. Then, each ball is assigned two numerical scores-one for eachimpact—from 1 (no visible damage) to 5 (substantial material displaced).These scores may be then averaged for each Example to produce the shearresistance numbers. These numbers may be then directly compared with thecorresponding number for a commercially available ball, having a similarconstruction including the same core and mantle composition and coverthickness for comparison purposes.

Impact durability may be tested with an endurance test machine. Theendurance test machine is designed to impart repetitive deformation to agolf ball similar to a driver impact. The test machine consists of anarm and impact plate or club face that both rotate to a speed thatgenerates ball speeds of approximately 155-160 mph. Ball speed ismeasured with two light sensors located 15.5″ from impact location andare 11″ apart. The ball is stopped by a net and if a test sample is notcracked will continue to cycle through the machine for additionalimpacts. For golf balls, if zero failures occur through in excess of 100impacts per ball than minimal field failures will occur. For layersadjacent to the outer cover, fewer impacts are required since the covertypically “protects” the inner components of the golf ball.

Golf ball Sound Pressure Level, S, in decibels (dB) and Frequency inhertz (Hz) may be measured by dropping the ball from a height of 113 inonto a marble (“starnet crystal pink”) stage of at least 12″ square and4.25 inches in thickness. The sound of the resulting impact is capturedby a microphone positioned at a fixed proximity of 12 inches, and at anangle of 30 degrees from horizontal, from the impact position andresolved by software transformation into an intensity in db and afrequency in Hz. Data collection is done as follows:

Microphone data is collected using a laptop PC with a sound card. AnA-weighting filter is applied to the analog signal from the microphone.This signal is then digitally sampled at 44.1 KHz by the laptop dataacquisition system for further processing and analysis. Data Analysiswas done as follows:

The data analysis is split into two processes:

a. Time series analysis that generates the root mean square (rms) soundpressure level (SPL) for each ball impact sound.

-   -   i. An rms SPL from a reference calibration signal is generated        in the same manner as the ball data.    -   ii. The overall SPL (in decibels) is calculated from the        reference signal for each ball impact sound.    -   iii. The median SPL is recorded based on 3 impact tests.

b. Spectral analyses for each ball impact sound

-   -   i. Fourier and Autoregressive spectral estimation techniques are        employed to create power spectra.    -   ii. The frequencies (in cycles/sec−Hz) from highest level peaks        representing the most active sound producing vibration modes of        each ball are identified.

Analysis of the cis, trans and vinyl content and degree of hydrogenationwas performed using either an FTIR method (and analysis of theabsorption intensities at about 740 cm-1 for cis, about 967 cm-1 fortrans and about 910 cm-1 for vinyl) or by 1H NMR.

The molecular weight (Mw) and Mw/Mn values for the PHPB compositionswere determined by Gel Permeation Chromatography

In view of the many possible embodiments to which the principles of thedisclosed compositions and methods, it should be recognized that theillustrated embodiments are only preferred examples and should not betaken as limiting the scope of the invention.

Example 1 Synthesis of Partially Hydrogenated Butadiene Rubber

0.24 g of tetrahydrofuran and 4.4 mmol of n-butyl lithium were added to2,400 g of cyclohexane in a 5 L-autoclave reactor. 400 g of a1,3-butadiene monomer was added and kept for 60 minutes ofpolymerization. The active terminal of the living polymer thus obtainedwas deactivated with 2,6-di-tert-butyl-4-methylphenol added in the samemole as the polymerization initiator, n-butyl lithium. The polymer thusobtained was a polybutadiene rubber of which the 1,2-vinyl bond contentof the butadiene unit was 11.9%, and the 1,4-trans content of thebutadiene unit was 49.9%, and the 1,4 cis content of the butadiene unitwas 38.2%, and the number average molecular weight was about 94,000. Themolecular weight (Mw) and % cis, vinyl and trans content are summarizedin Table 1.

In order to carry out the hydrogenation, 2,800 g of the polymer solutioncontaining 400 g of the polybutadiene rubber was added to a 5L-autoclave reactor and then heated to 70° C. 60 ml of a lithium hydridesuspension (0.1M in cyclohexane) and 0.2 mmol of bis(cyclopentadienyl)titanium(IV) dichloride were added into the reactor so that the LiH/Timole ratio was 30/1. And the hydrogen gas was blown into the reactor.The hydrogenation was performed in the reactor with hydrogen pressure of10 kgf/cm2 with stifling at 400 rpm. After the completion of thereaction, the reactor was cooled down with the pressure lowered to theambient pressure. The catalyst was removed by washing with aqueoushydrochloric acid, and the polymer was recovered via steam stripping,under conditions typical for hydrogenated polymers

As also summarized in Table 1, 1H-NMR analysis of the hydrogenatedpolymer showed that 48% of the double bonds in the polybutadienestarting material was saturated after hydrogenation.

Example 2 Synthesis of Partially Hydrogenated Butadiene Rubber

0.24 g of tetrahydrofuran and 4.1 mmol of n-butyl lithium were added to2,400 g of cyclohexane in a 5 L-autoclave reactor. 400 g of a1,3-butadiene monomer was added and kept for 60 minutes ofpolymerization. The active terminal of the living polymer thus obtainedwas deactivated with 2,6-di-tert-butyl-4-methylphenol added in the samemole as the polymerization initiator, n-butyl lithium. The polymer thusobtained was a polybutadiene rubber of which the 1,2-vinyl bond contentof the butadiene unit was 12.0%, and the 1,4-trans content of thebutadiene unit was 49.7%, and the 1,4 cis content of the butadiene unitwas 38.3%, and the number average molecular weight was about 105,000.The molecular weight (Mw) and % cis, vinyl and trans content aresummarized in Table 1.

In order to carry out the hydrogenation, 2,800 g of the polymer solutioncontaining 400 g of the polybutadiene rubber was added to a 5L-autoclave reactor and then heated to 70° C. 60 ml of a lithium hydridesuspension (0.1M in cyclohexane) and 0.2 mmol of bis(cyclopentadienyl)titanium(IV) dichloride were added into the reactor so that the LiH/Timole ratio was 30/1. And the hydrogen gas was blown into the reactor.The hydrogenation was performed in the reactor with hydrogen pressure of10 kgf/cm2 with stifling at 400 rpm. After the completion of thereaction, the reactor was cooled down with the pressure lowered to theambient pressure. The catalyst was removed by washing with aqueoushydrochloric acid, and the polymer was recovered via steam stripping,under conditions typical for hydrogenated polymers

As also summarized in Table 1, 1H-NMR analysis of the hydrogenatedpolymer showed that 47% of the double bonds in the polybutadienestarting material was saturated after hydrogenation.

Example 3 Synthesis of Partially Hydrogenated Butadiene Rubber

0.24 g of tetrahydrofuran and 3.5 mmol of n-butyl lithium were added to2,400 g of cyclohexane in a 5 L-autoclave reactor. 400 g of a1,3-butadiene monomer was added and kept for 60 minutes ofpolymerization. The active terminal of the living polymer thus obtainedwas deactivated with 2,6-di-tert-butyl-4-methylphenol added in the samemole as the polymerization initiator, n-butyl lithium. The polymer thusobtained was a polybutadiene rubber of which the 1,2-vinyl bond contentof the butadiene unit was 12.2%, and the 1,4-trans content of thebutadiene unit was 49.6%, and the 1,4 cis content of the butadiene unitwas 38.2%, and the number average molecular weight was about 118,000.The molecular weight (Mw) and % cis, vinyl and trans content aresummarized in Table 1.

In order to carry out the hydrogenation, 2,800 g of the polymer solutioncontaining 400 g of the polybutadiene rubber was added to a 5L-autoclave reactor and then heated to 70° C. 60 ml of a lithium hydridesuspension (0.1M in cyclohexane) and 0.2 mmol of bis(cyclopentadienyl)titanium(IV) dichloride were added into the reactor so that the LiH/Timole ratio was 30/1. And the hydrogen gas was blown into the reactor.The hydrogenation was performed in the reactor with hydrogen pressure of10 kgf/cm2 with stifling at 400 rpm. After the completion of thereaction, the reactor was cooled down with the pressure lowered to theambient pressure. The catalyst was removed by washing with aqueoushydrochloric acid, and the polymer was recovered via steam stripping,under conditions typical for hydrogenated polymers

As also summarized in Table 1, 1H-NMR analysis of the hydrogenatedpolymer showed that 47% of the double bonds in the polybutadienestarting material was saturated after hydrogenation.

TABLE 1 Molecular weight (Mw), % Vinyl, % Trans content of thePolybutadien Starting Material and Degree of Hydrogenation of theExemplified PHPB Compositions Ex. 1 Ex. 2 Ex3 Mw 94,000 105,000 118,0001,2-Vinyl (%) 11.9 12.0 12.2 1,4-Trans (%) 49.9 49.7 49.6 1,4-Cis (%)38.2 38.3 38.2 Hydrogenation 48% 47% 47%

What is claimed is:
 1. A golf ball comprising; I. a core; II. one ormore mantle layers; and III. an outer cover layer, and wherein one ormore of said core, one more mantle layers or outer cover layer comprisesa partially hydrogenated polybutadiene having a viscosity at 200° C. ofless than about 5,000 Pa-sec and a storage modulus (G′) at 1 Hz and 25°C. of greater than about 1×10⁷ dyn/cm².
 2. The golf ball of claim 1wherein said partially hydrogenated polybutadiene is prepared byhydrogenation of a polybutadiene containing of from about 20 to about 80mol percent trans 1,4-addition, of from about 10 to about 70, preferablyof from about 20 to about 60, and more preferably of from about andabout 25 to about 45 mole percent cis 1,4-addition and a weight averagemolecular weight of from about 50,000 to 300,000 and wherein thehydrogenation results in a partially hydrogenated polybutadiene whereinof from about 25 to about 75, % of the double bonds in the originalpolybutadiene have been hydrogenated and are thus saturated.
 3. The golfball of claim 1 wherein said partially hydrogenate polybutadiene iscrosslinked by a crosslinking composition comprising i) one or moreperoxides; ii) a zinc or magnesium salt of an unsaturated fatty acidshaving 3 to 8 carbon atoms selected from the group consisting of acrylicacid, methacrylic acid, maleic acid, stearic acid, fumaric acid,palmitic acid and mixtures thereof; and iii) a peptizer selected fromthe group consisting of an organic sulfur compound, a metal salt of anorganic sulfur compound, a non-metal salt of an organic sulfur compound,and any and all combinations thereof.
 4. The golf ball of claim 1wherein said partially hydrogenated polybutadiene further comprises anadditional polymer component selected from the group consisting of; A.one or more carboxylated elastomers selected from the group consistingof; a) a copolymer selected from the group consisting of carboxyaltedpolybutadiene, carboxylated styrene-butadiene copolymer, carboxylatedacrylonitrile-butadiene copolymer and mixtures thereof; b) a graftedelastomer selected from the group consisting of maleated polybutadienes,maleated styrene butadiene rubbers (“SBR”), maleatedacrylonitrile-styrene-butadiene (“ABS”) rubbers, maleatednitrile-butadiene rubbers (“NBR”), maleated hydrogenated acrylonitrilebutadiene rubbers (“HNBR”), methylmethacrylate butadiene styrene (“MBS”)rubbers, carboxylated ethylene-propylene-diene monomer rubbers,carboxylated styrene-acrynitrile rubbers (“SAN”), carboxylated ethylenepropylene diene rubbers (“EPDM”), acrylic grafted silicone rubbers, andcombinations thereof; and c) any and all combinations of i and ii; B. apolyalkenamer rubber selected from the group consisting of polybutenamerrubber, polypentenamer rubber, polyhexenamer rubber, polyheptenamerrubber, polyoctenamer rubber, polynonenamer rubber, polydecenamer rubberpolyundecenamer rubber, polydodecenamer rubber, polytridecenamer rubberand any and all combinations thereof; and C. any and all combinations ofA and B.
 5. The golf ball of claim 3 wherein; A. said carboxylatedelastomer composition has; i) a melt flow index (MFI) of from about 1 toabout 80 g/10 min.; ii) a material hardness of from about 20 to about 90Shore D; and iii) a flex modulus of from about 1 to about 120 kpsi.; andcomprises; a) a carboxylated nitrile rubber which is a copolymer ofbutadiene, acrylonitrile and one or more α,μ-unsaturated carboxylicacids having an elastomer backbone having the following formula

 and which is substituted by one or more carboxy groups selected fromthe group consisting of those derived from acrylic acid, methacrylicacid, fumaric, acid, maleic acid and itaconic acid; or b) a graftedpolyisoprene selected from the group consisting of i) apolyisoprene-graft-maleic anhydride having the following chemicalstructure:

ii) a polyisoprene-graft-maleic anhydride monoester of maleic anhydridehaving the following chemical structure

and iii) all mixtures of i and ii.
 6. The golf ball of claim 3 whereinsaid carboxylated elastomer or said polyalkenamer is crosslinked by acrosslinking composition selected from the group consisting of; a) oneor more basic metal salts selected from the group consisting of metalformates, metal acetates, metal nitrates, metal carbonates, metalhydrogen carbonates, metal oxides, metal hydroxides, metal alkoxides,metal stearates and mixtures thereof; b) a mixture comprising i) one ormore peroxides; ii) a zinc or magnesium salt of an unsaturated fattyacids having 3 to 8 carbon atoms selected from the group consisting ofacrylic acid, methacrylic acid, maleic acid, stearic acid, fumaric acid,palmitic acid and mixtures thereof; and iii) a peptizer selected fromthe group consisting of an organic sulfur compound, a metal salt of anorganic sulfur compound, a non-metal salt of an organic sulfur compound,and c) any and all combinations of a) and b).
 7. The golf ball of claim1 wherein said core; a) has a diameter of from about 0.5 to about 1.62inches; b) has a PGA compression of less than about 100; and c)comprises a peptizer selected from the group consisting of an organicsulfur compound, a metal salt of an organic sulfur compound, a non-metalsalt of an organic sulfur compound, and any and all combinationsthereof.
 8. The golf ball of claim 1 wherein said core; a) has adiameter of from about 0.7 to about 1.60 in; b) has a PGA compression ofless than about 90; and c) further comprises one or more core layerseach exhibiting a different hardness wherein the difference in hardnessbetween each core layer is greater than 5 units of Shore D.
 9. The golfball of claim 8 wherein the hardness of the core center and eachsequential core layers increases progressively outwards from the centerto the outer core layer.
 10. The golf ball of claim 8 wherein thehardness of the core center and each sequential core layers decreasesprogressively outwards from the center to the outer core layer.
 11. Thegolf ball of claim 1 wherein said cover composition comprises a polymerselected from the group consisting of a) a thermoset polyurethane; b) athermoplastic polyurethane; c) a thermoset polyurea; d) a thermoplasticpolyurea; e) a multicomponent blend composition (“MCBC”), the MCBCcomprising (A) a block copolymer; and (B) one or more acidic polymers;and (C) one or more basic metal salts present in an amount to neutralizeat greater than or equal to about 30 percent of the acid groups ofComponent (B); and f) any and all combinations thereof.